Tbi swap build thread

[cjracing15]

Originally Posted by 408cuda

Hi guys. Found this site after extensively searching the web on TBI swaps and it seems like a great source of info. I am in the process of converting a friends 59 Chevy Apache pickup from a straight 6 to 350 TBI out of an 88 Chevy 2wd pickup. We are using the donor rigs wiring harness. Anyway, I have the mounts fabbed and engine in and and getting close to trying to wire it up. We stripped the harness and all sensors from the donor but the part I am having trouble understanding is what exactly I need to power up for wires from the harness? I plan to add a 6 lug fuse block just for this purpose. I have some wiring diagrams that are helpful, but don't know what wires I NEED hooked to the fuse block, or elsewhere? We are using the 5 speed manual from donor as well and since we are using the stock wiring do I need to do anything to work the VSS? . For a gas tank we were thinking of an 88 Blazer which dimensionally looks doable, and takes the same pump/wiring etc..

Thanks for your time,
Chad

Go back to the first page of this thread. It's not a diagram but a list of wire colors and what they do in the harness. If you use the stock harness you will have to strip all if the harness tape off and trace the wires down. It's not that hard. Good luck if you have any questions just ask.
Jamie

[408cuda]

Sorry for the dumb questions guys. I looked the thread over again start to finish and it covers most of all of it, great info! I have been reading about it so much my mind is numb. Anyway, I have a wiring schematic for a 90 that seems to be pretty accurate to our 88 that has helped. We stripped the harness down today and unloaded the known unnecessary wiring but....

Wires/connectors I am unsure of at the moment:

Two wire connector that dumped at the front of the engine by the temp sender. Pink/black (splices into A6 IIRC) and brown I believe. Was this for air pump or something? Doesn't appear to have been hooked up anytime recently. I don't think it's AC related, looks like a different connector.

Tan 18g wire that went into the cab at the bulkhead under the master cyl. Dumps near the dstrib. Don't think it was hooked on donor.

2nd purple single wire O2 sensor connector on pass side. Ditch or keep for future?

VSS wires coming from bulkhead to trans, purple and yellow I believe. Where do I hook these? I assume coming from near the fuse box at least one is powered? Not sure what I need to do being a 5 spd, and wires sound different than most I have read.

Neutral safety wires also go into bulkhead and not ecm. If I remember right the colors were blue, and green. I'm guessing one must have went to the clutch pedal somehow?

Lastly, there is a large red 12 or 10g wire that plugs in near the ECM under the dash. Goes to the gauges and power strip? needed?

So if I understand correctly all I need from the 3rd (white in my case) connector near the ECM is the diagnostic port wires, orange, white/black (data) black/white (ground) red fuel pump test wire, and brown/white SES wire (one side to a 12v light, other grounded) Am I on the right track?

We have the 747 ECM, 88 1500 truck harness, and 5 speed manual. I don't have the service manual yet (I know) but think we can get it going off what I have dug up.

Also curious if I should wire in a 3-wire o2 sensor while it's easy to do or should I even bother? Engine does have headers and I remember reading a TBI source that recommended upgrading sensors when using headers. I know single wire o2's are slow but if the 3 wire is a waste on the older FI system we'll leave it be.

Thanks in advance! Sorry for the laundry list of dumb questions.

[rfmaster]

Wires/connectors I am unsure of at the moment:
Q1
Two wire connector that dumped at the front of the engine by the temp sender. Pink/black (splices into A6 IIRC) and brown I believe. Was this for air pump or something? Doesn't appear to have been hooked up anytime recently. I don't think it's AC related, looks like a different connector.
A1)==================================================================
If original harness was sourced from a 1227747 TBI truck then it is Air Diverter solenoid connector:
A6 + 12Vdc Pink-Black (Ignition hot)
C2 Air Diverter Brown
====================================================================
Q2
Tan 18AWG wire that went into the cab at the bulkhead under the master cyl. Dumps near the dstrib. Don't think it was hooked on donor.

A2)==================================================================
Hard to tell, if it has a white stripe it can be an EST!
===================================================================
Q3
2nd purple single wire O2 sensor connector on pass side. Ditch or keep for future?

A3)==================================================================
Pre 1992 trucks used single wire O2 - keep it as O2 used tan wire tied to D6 as O2 ground and
Purple D7 as O2 sensor input.
===================================================================
Q4
VSS wires coming from bulkhead to trans, purple and yellow I believe. Where do I hook these? I assume coming from near the fuse box at least one is powered? Not sure what I need to do being a 5 spd, and wires sound different than most I have read.

A4)==================================================================
The reason for different color wires that most applications used buffer DRAC module between VSS and ECM. However all this VSS nonsense is easy to get around. If you are using 7747 ECM you need two pulse (2000 pulses per mile) square wave VSS Part # 2PRS from JTR or equivalent. Connect purple wire to ECM VSS input A10 and the other wire to electric ground –A11. VSS is done. Internally ECM has 5.1k pull up resistor on line A10 which keeps VSS line high. As speedometer cable turns VSS sensor pulls this line down and ECM is able to detect these voltage transitions. It is important to have operable VSS – ECM uses this for a number control functions!
===================================================================
Q5
Neutral safety wires also go into bulkhead and not ECM. If I remember right the colors were blue, and green. I'm guessing one must have went to the clutch pedal somehow?
A5)==================================================================
That is not true - ECM pin B10 is P/N input. For automatics a simple circuit which uses relay, diode and wire can be easily configured. http://www.painlessperformance.com/M...nstruction.pdf
For a five speed leave ECM pin B10 open – do no connect to anything.
===================================================================
Q6
Lastly, there is a large red 12 or 10g wire that plugs in near the ECM under the dash. Goes to the gauges and power strip? needed?
A6)==================================================================
Hard to tell – post a picture of these wires
===================================================================

Q7
So if I understand correctly all I need from the 3rd (white in my case) connector near the ECM is the diagnostic port wires, orange, white/black (data) black/white (ground) red fuel pump test wire, and brown/white SES wire (one side to a 12v light, other grounded) Am I on the right track?

A7)==================================================================
For ALDL connector you’ll need the following wires:
Pin # | Color | Function
A | Blk-White | Ground
B | White | Diagnostic enable
C | Brown | Air Diverter
D | n/c
E | Orange | ALDL serial data
F | Tan | TCC – only for A/T

For SES Pin A5 Brown-white to one side of SES light and the other side to +12 V in run/start . Make sure that your SES light does not require too much current – 20 mA or less.
===================================================================


We have the 747 ECM, 88 1500 truck harness, and 5 speed manual. I don't have the service manual yet (I know) but think we can get it going off what I have dug up.

Q8
Also curious if I should wire in a 3-wire o2 sensor while it's easy to do or should I even bother? Engine does have headers and I remember reading a TBI source that recommended upgrading sensors when using headers. I know single wire o2's are slow but if the 3 wire is a waste on the older FI system we'll leave it be.

A8)==================================================================
I run four wire O2 sensor – ground return reference wire remove any possibility of a poor ground return path from O2 sensor readings, especially with long tube headers that may cool. O2 sensor must remain above 600F to provide correct voltage readings. The other two wires are used for heater coil. A simple relay tied to ignition on circuit turns on O2 heater. Use AC-Delco AFS-74 (25312179) for best results


//RF

[cjracing15]

Hey the only dumb qeustion is one you do not ask. I am sorry if I made it seem like you asked a dumb question.(That is not what I meant at all)
This is what I started this thread for was to try to answer questions about a TBI swap.

I am like rf if you can get a pic one of us might can figure out what the mystery red wire is.

This is the diagram I used.



If you have any other questions just ask

[408cuda]

Ok guys, did some more ciphering on the harness yesterday. I think I got most of it traced out. This is what my 3rd (white connector that leads to gauges and ALDL) near the ECM looks like, and how I interpret it.

A-A9 wht/blk=ALDL diag enable
B-A5 brwn/wht=SES light ground
C-empty
D-A7 tan/blk=TCC/shift indicator
E- To RH injector, red=12v keyed power?
F-A6 pnk/blk= 12v ign " "
G-empty
H- To air diverter connector, brown
J-C9 prpl/wht= crank input needed for anything?
K-B10 orng/blk=Park/neutral... this is empty on ours, had no wires coming out
L-RH o2 sensor, prpl. Not hooked up
M-A10=VSS, brown. Did this go to the buffer under the dash? I thought the other two controlled VSS?
N-Ground, blk/wht
P-Fuel pump relay, red/wht
R-A8=ALDL data

Also have a light blue/blk wire in the ALDL connector that I snipped out of the donor harness under the dash, couldn't see where that went. Guessing I can lose that.

And in this shot you can see the red mystery wire that comes in with the ECM connectors. One side goes to the power strip/block with a fuseable link.



Wires I have left on the bulkhead/fuse block side.
Blue-green NSS wires, or at least that's what I thought they were. Maybe they go to the gauges?
Purple/wht-yellow VSS wires, into cab through VSS buffer?
Tan, unknown. Looks like it was long enough to reach the fuel pump relay, or maybe IAC? Anyway I looked at all the sensors and I just don't see anything missing. Distrib has all of it's wires too.
Pink, coil hot, 12v start/run
Dk Green, temp sender goes to front of L cyl head, for factory gauge I presume? I was thinking of putting in an aftermarket gauge here.
Purple, starter engage wire 12v
Red, goes to power block. I was thinking of using this for 12v power to the ign key?

I ended up finding a service manual in my shop on the book shelf (d'oh) and it helped some, but I still didn't see anything useful for under the dash. Under the wiring for the air diverter it says "if equipped" does that mean I can ditch it? It wasn't hooked on our donor and the truck ran pretty good.I see those valves cost a few bucks.

Also, I don't recall any from of speedo cable provision on this trans, can I still use an aftermarket VSS converter?

Thanks for all the help, I know you guys must get sick of the same questions but I'm not very familiar with these trucks or systems, and wiring isn't my forte' either.

Sorry to hijack your post cj! How are you making out on yours?

[rfmaster]

Cuda

I have to spend a bit time and draw a schematic based on your information - as starting point, subject to further revisions. Soooo, hang on tight - it is always fun to do a bit of reverse engineering to get things working! Meanwhile XYL wants to have quality time...

CU

//RF

[cjracing15]

I am like rf I am going to have to look some stuff up to figure everything out on hte wires that you have pictured. This is what I do know by just looking at the wires.

On the wiers you have left Going from left to right.

BLU and the lt green go to the back-up liight switch on the bottom of the stearing collumn. I know this one.

The purple could be the wire that goes to the starter you can trace this back to the computer to see if it is. If it is it will go back to C-9 on your computer plugs.??

The dark green looks to me to be an ac wire they are dark green. ??

The heavy red looks like it should of gone to the starter. That would make sense if it was on the power block from the starter on the 88 truck. ??

The black wire looks like a ground wire for the aldl link or a ground peorid. ??

The tan could be the o2 sensor. Check D-6 on hte computer plug to see. ??

Pink wire looks like the coil wire . ??

Prpl and white This really looks like the crank signla wire to me. I would trace it back to see if it went to C-9 ??

The yellow wire looks to me to be the coolant temp sensor wire. I would trace it back to see if it went to C-10. ??

I hope this help ya.

I am going to get back on mine tomarow if I don't get called into work.

Good luck, Jamie

[rfmaster]

This posting will deal with ECM side of wiring harness. A simple TBI wiring diagram can be found here:



Regarding 3rd connector - I have couple of questions - please see my list below:


3rd Connector ECM Wire Function
A A9 white/black ALDL diagnostics enable
B A5 brown/white SES light (pulled to ground by ECM)
C Empty
D A7 tan/black TCC/shift indicator (not used with std transmission)
E To RH injector, red=12v keyed power?
YES, connect to 15 Amp ECM Fuse #1 via separate relay – more on this later
F A6 pink/black 12v ECM Fuse #1 Hot in RUN/START
G Empty
H C2 Brown To air diverter valve connector.
You can ditch it if you are not using AIR pump.
J C9 Purple/white crank input needed for anything? YES
K B10 orange/black Park/neutral... this is empty on ours, had no wires coming out. OK
L ????? Purple RH o2 sensor, prpl. Not hooked up.
Does go down into engine bay? Can you find the other end?
M A10 Brown VSS, brown. Did this go to the buffer under the dash?
(Yes, it went to DRAC module) But now tie to one of the two wires that will connected to after market VCC module, the other to ground
N ????? black/white Ground
P red-white Fuel pump relay, red/wht
(Which terminal of Fuel pump relay???)
R A8 Orange ALDL data


Also have a light blue/blk wire in the ALDL connector that I snipped out of the donor harness under the dash, couldn't see where that went. Guessing I can lose that. (YES)
And in this shot you can see the red mystery wire that comes in with the ECM connectors. One side goes to the power strip/block with a fuseable link.
In GM wiring practice solid red indicates direct connection to battery (10-12 AWG), solid orange indicates fused battery line and pink with various color stripes indicates fused ignition line.


Since you are putting into older vehicle I would install an auxiliary relay panel (see Painless Part# 70107 Fuse Block / 7 Circuits kit http://www.painlessperformance.com/M...nstruction.pdf).
This panel would off load current that otherwise would have to travel through 50 year old ignition switch!

More to come... Just hang on tight.
//RF

[cjracing15]

That is a great diagram RF. Thanks for the time.

[408cuda]

Originally Posted by rfmaster

This posting will deal with ECM side of wiring harness. A simple TBI wiring diagram can be found here:



Wow, thanks for all the effort, that's excellent!

Regarding 3rd connector - I have couple of questions - please see my list below:

3rd Connector ECM Wire Function
A A9 white/black ALDL diagnostics enable
B A5 brown/white SES light (pulled to ground by ECM)
C Empty
D A7 tan/black TCC/shift indicator (not used with std transmission)
E To RH injector, red=12v keyed power?
YES, connect to 15 Amp ECM Fuse #1 via separate relay – more on this later
F A6 pink/black 12v ECM Fuse #1 Hot in RUN/START
G Empty
H C2 Brown To air diverter valve connector.
You can ditch it if you are not using AIR pump.
J C9 Purple/white crank input needed for anything? YES
K B10 orange/black Park/neutral... this is empty on ours, had no wires coming out. OK
L ????? Purple RH o2 sensor, prpl. Not hooked up.
Does go down into engine bay? Can you find the other end?

Yes, it has the same connector as the LH o2 sensor but this one was not hooked up, ends near pass side cyl head, traces back to instrument cluster on donor (I ripped apart donor harness in truck today)

M A10 Brown VSS, brown. Did this go to the buffer under the dash?
(Yes, it went to DRAC module) But now tie to one of the two wires that will connected to after market VCC module, the other to ground
N ????? black/white Ground
P red-white Fuel pump relay, red/wht
(Which terminal of Fuel pump relay???)

Not sure which terminal but 99% positive I traced that one back to the ALDL and read it was fuel pump test.

R A8 Orange ALDL data


Since you are putting into older vehicle I would install an auxiliary relay panel (see Painless Part# 70107 Fuse Block / 7 Circuits kit http://www.painlessperformance.com/M...nstruction.pdf).
This panel would off load current that otherwise would have to travel through 50 year old ignition switch!
//RF

My friend/owner of the truck came over today and we went through his factory wiring. I was thinking we will use a new ignition switch and distribute power through it. Nothing will actually be going through his wiring this way. We have it stripped down to just a few wires left on his that we figured we can power off the new, or even existing fuse box. The items left are...

Headlights
Turn signals/brakes etc
Cig lighter
Radio
Horn

That's about all there is to this thing. There are a grand total of 4 wires going to his fuse box now! Pretty simple.

I was thinking of using the red 10g hot in from the power strip for the BAT side a switch.
Purple 10g for to starter on START terminal of said switch
A jumper from that wire to fuse block, C9 prple/wht on the other side of that fuse.
New 10g wire from ACC or RUN terminal on ignition switch to power up new fuse block.
And then my wires needing 12v in RUN can be hooked to new fuse box.

Does this sound acceptable? Like I said, I am no wiring master.

I traced a few of the unknowns left today and found the green wire was temp sender on head (was hooked on old engine) went to the gauge cluster (that was what I was unsure of on that one)
Tan that goes to nowhere, also goes to gauges
All VSS wires go into cluster harness
Blue and light green wires from trans....blue to switched hot in fuse and green doubles around and heads back out to engine bay, no clue from there but guess it's too back-up lights as cj suggested?
Also forgot brown wire last night. Goes from alt to cluster for volt gauge I reckon?
And fuel pump harness has a pink wire from pump to the cluster that I initially thought was a hot but if power is Tan/white via orange, this must have been for the fuel gauge?
The rest I think are pretty much known.

Thanks a bunch guys. Can't wait to fire her up! Going to button it up and plumb some fuel soon just to see if it will ignite. After that it gets blown apart and goes out for paint. Here is the rig it's in.

[408cuda]

Forgot to ask. I have to relocate the knock sensor for header clearance. Is the fuel pump provision acceptable even though it's not machined or open on this block? Don't see anywhere else it will fit.

Thanks!

[rfmaster]

CUDA

I am still drawing few more diagrams based on your last response. I think that you are almost there. Nice truck!

/?RF

[rfmaster]

Originally Posted by 408cuda

Forgot to ask. I have to relocate the knock sensor for header clearance. Is the fuel pump provision acceptable even though it's not machined or open on this block? Don't see anywhere else it will fit.

Thanks!

A typical TBI system uses electrical fuel pump, which GM mounted in tank or alternatively, inline electrical fuel pump can be used instead. Typical system EFI system requires three fuel lines between tank and engine bay.
Supply line - 3/8" is used by Fuel Pump (FP) to supply fuel to TBI inlet. Please make sure that you have FP that can supply a minimum of 20 PSI. Do not go to crazy with fuel pressure as excess fuel will be bypassed and returned back to the gas tank via return line 5/16" or 3/8". Excessive fuel pump pressure tends to increase fuel temperature, which is not good - this will increase fuel vapor pressure. Third fuel line is connected to charcoal canister that connects to TBI (1/4") line.

Main DC power distribution.



//RF

[rfmaster]

Originally Posted by 408cuda

My friend/owner of the truck came over today and we went through his factory wiring. I was thinking we will use a new ignition switch and distribute power through it. Nothing will actually be going through his wiring this way. We have it stripped down to just a few wires left on his that we figured we can power off the new, or even existing fuse box. The items left are...

Headlights
Turn signals/brakes etc
Cig lighter
Radio
Horn

That's about all there is to this thing. There are a grand total of 4 wires going to his fuse box now! Pretty simple.

I was thinking of using the red 10g hot in from the power strip for the BAT side a switch.
Purple 10g for to starter on START terminal of said switch
A jumper from that wire to fuse block, C9 prple/wht on the other side of that fuse.
New 10g wire from ACC or RUN terminal on ignition switch to power up new fuse block.
And then my wires needing 12v in RUN can be hooked to new fuse box.

Does this sound acceptable? Like I said, I am no wiring master.

I traced a few of the unknowns left today and found the green wire was temp sender on head (was hooked on old engine) went to the gauge cluster (that was what I was unsure of on that one)
Tan that goes to nowhere, also goes to gauges
All VSS wires go into cluster harness
Blue and light green wires from trans....blue to switched hot in fuse and green doubles around and heads back out to engine bay, no clue from there but guess it's too back-up lights as cj suggested?
Also forgot brown wire last night. Goes from alt to cluster for volt gauge I reckon?
And fuel pump harness has a pink wire from pump to the cluster that I initially thought was a hot but if power is Tan/white via orange, this must have been for the fuel gauge?
The rest I think are pretty much known.

Thanks a bunch guys. Can't wait to fire her up! Going to button it up and plumb some fuel soon just to see if it will ignite. After that it gets blown apart and goes out for paint.

I am trying to follow what you are trying to do - it is very difficult without schematics or diagrams. Can you draw a diagram of what you are trying to do and post it. I know it is tough enough, but I am just trying to prevent shorts and burned wires and 'oh s*&*' moments!


You can relocate Knock Sensor (KS) to the other side, but it must be screwed into oil pan rail (water jacket drain plug) to be effective! KS is a calibrated microphone, tuned for a knock frequency found in a specific engine family.

//RF

[gchemist]

Here a good website source for TBI swaps: http://users.sfo.com/~eagle/howell.html

[408cuda]

Hey Guys, been working late and haven't had time to post anything. I wired it up as shown here, not sure if I forgot something but this should about cover it. Forgive the grade school artwork. All of the other ECM and sensor wires are untouched if not noted, everything is hooked up as it was other than the o2 sensor, plan to wire a 3 or 4 wire but probably not until after we fire it (will use the 1 wire temporarily)

The truck has an electric speedo and no VSS buffer that I can find and I traced the wiring under the donor dash to the cluster. We are trying to make the 88 speedo work in the 59 so that would help put that fire out. Will I need to do anything with the VSS wires to get it to run? We hope to test fire it soon. I ran new plug wires last night and buttoned up the under dash wiring. Just need to move the knock sensor and slide the donor tank under temporarily and plumb it up and she should be about ready. I can't move the KS to the other side because the headers are block huggers and dump right into the center on both sides. I might see if I can mod the KS wire/connector to clear the header as it isn't hitting by much.

If something looks off I'm all ears.

Thanks again,
Chad

[rfmaster]

1) ECM B1 & C16 to battery - must be always hot (see chart and diagram).
2) You do not need VSS to get the engine fired, but you'll need it once you get it into driving condition.
3) Many other circuits must be wired-up before you can really drive it.... (Brake, turn, back up, etc)

//RF

[D13]

Depending on which 88 (NBS = pickup) you got it from the trans may supply pulses to the ECM which then filters it to run the speedo. The other version (OBS = burb/blazer) uses cable drive speedo with a VSS output box hung on it. Either way you need the appropriate input. Old style uses 4000 pulse per mile and the new one uses like a 132,000 signal divided and dropped down for various systems. There were a couple years of crossovers where Burbs has cable drive trans rather than electronic outputs. Need to make sure your trans/dash/ecm all play together.

[chevymotocross]

Originally Posted by cjracing15

Yes sir been in the service feild going on nine years now. Mostly comercial refrigeration, but I do residential on the side.

HVAC guy here too. We do strictly residential heating/cooling... no refrigeration Actually just started out in the trade 3 months ago. Like it lots so far and the pay is good.

[cjracing15]

Originally Posted by chevymotocross

HVAC guy here too. We do strictly residential heating/cooling... no refrigeration Actually just started out in the trade 3 months ago. Like it lots so far and the pay is good.

Good to see anouther hvac guy on here. I bet it is cold in CT. We are going to start doing spring start ups next month here in TN. it's 65 here today.

[chevymotocross]

Originally Posted by cjracing15

Good to see anouther hvac guy on here. I bet it is cold in CT. We are going to start doing spring start ups next month here in TN. it's 65 here today.

Lmao, I could only DREAM of 65 degree temps here in CT right now. Today's high was 25!

[cjracing15]

Originally Posted by chevymotocross

Lmao, I could only DREAM of 65 degree temps here in CT right now. Today's high was 25!

[rfmaster]

GM to all from wet So-Cal

This morning I had a bit of free time - here is headlight circuit diagram for CUDA using remote relays to switch headlight circuit. Use BOSCH style relays and 12 (or 10) AWG SXL (SAE J-1128) automotive grade wire to bring current to your headlights. On relay control side you can use smaller gauge wire (16 to 18 AWG) to make harness a bit easier. Unfortunately, many use commonly available THM grade wire which is not suitable for automotive applications due to extreme temperatures. Make sure to use weather pack style inline fuses or fuse links! Absence of fuses can lead to fires!

Ignition circuit and ECM interconnect is to follow... Hmmm we are getting lighting and thunder here - very unusual!

[rfmaster]

Basic ignition and power



//RF

[408cuda]

Just a quick update. It lives! Had it running 3 or 4 times today. Sounds decent but did trip the SES light for the o2 sensor which was no surprise as it's jb welded into ~2' of ex pipe and the other side is open header. This was just to see if would even run. Lots of odds and ends to do now but we're on our way. Pretty uneventful test fire overall. We hooked the donor tank up under it and once it had fuel psi to the TB she took right off.

Checked the alt and only showed about 12.5v, need to look into that still.

rf, the diagrams are amazing. The ignition one will really be a great help to those thinking of doing this. I plan to study the headlights and will put to use when we get to that. Thanks again!

Hope I didn't steal your thread cj, but another tbi swap running and you guys were a big help. More questions to follow I'm sure.