another idiot with vss speedo issues.

[Rascal_one2001]

I am running a 4l80e with a standalone computer that has a speedo out put that is adjustable so can go straight to a speedo. The issue I am having is I need to know which pole is which. I know one is + one is - one is speedo signal.

[Rascal_one2001]

I think the solo pin is + middle ground and last signal is that correct?

[hatzie]

Do you have a whole 90-91 Instrument cluster bucket or just the speedo head?
Hopefully you have the whole cluster.
According to both the 1990 & 1991 GM RV 10-30 Light Truck wiring manuals...
a LT-BLUE/BLACK circuit 284 speedo signal wire runs between one of the middle terminals on the DRAC and Instrument Cluster connector #C230 Terminal 18.

If you have the whole 90-91 instrument cluster bucket just hook the TCM VSS output to terminal 18 on the Instrument cluster plug and have done with it. No need to butcher the internal cluster bucket harness that way.

[slimneverdies]

What setup do you have for a standalone? I'm doing the same thing to my c30. So all I need is a 90-91 speedo to get a working setup to to the cluster from the standalone?

[72MARIO]

Can you please post pictures and follow up on how this works out for you. I am helping my dad put a 4l80 behind his 468 we got the tci setup including the remote tps.

[Rascal_one2001]

I am going to pick up some more parts today, will keep you updated on progress. I have the ez-tcu has a one wire adjustable wave speedo output.

[Rascal_one2001]

ok speedo works great with just a + - and signal from the ez-tcu. I used very crude wiring since I couldn't find my box of alligator clips But 100% finctional.

[slimneverdies]

Originally Posted by Rascal_one2001

ok speedo works great with just a + - and signal from the ez-tcu. I used very crude wiring since I couldn't find my box of alligator clips But 100% finctional.
Attachment 1374470

That's great that you didn't have to rewire or buy any extra components. I was starting to believe that it would be a little tedious to get everything up and running.

[Rascal_one2001]

Now I am rebuilding my cluster and going to cut out the back so the electronic speedo will fit. Going to solder on wires and steal + and - from the volt gauge and removable connection for the vss so I can take the cluster out in the future.

[Rascal_one2001]

Cluster modification is all done a ran on it today 100% perfect. Only thing I can see as a future issue is that if I loose traction I max out my speedo against the trip button so may end up breaking off the needle.

[hatzie]

Don't think the driver motor has enough chutzpah to snap the needle. The driver motor might not like it tho.

[slimneverdies]

Originally Posted by hatzie

Do you have a whole 90-91 Instrument cluster bucket or just the speedo head?
Hopefully you have the whole cluster.
According to both the 1990 & 1991 GM RV 10-30 Light Truck wiring manuals...
a LT-BLUE/BLACK circuit 284 speedo signal wire runs between one of the middle terminals on the DRAC and Instrument Cluster connector #C230 Terminal 18.

If you have the whole 90-91 instrument cluster bucket just hook the TCM VSS output to terminal 18 on the Instrument cluster plug and have done with it. No need to butcher the internal cluster bucket harness that way.

Ok, I just picked up a cluster from a 91 Burban and need a little assistance on what to do. I'm also running the TCI ez-tcu and TPS. Is the DRAC located near the gauges because I didn't find it on this Burban?





I also would like to add this gauge in the cluster and needed to know how does the gas gauge work with the cluster I have now...
http://gmsports.com/content/new-tach...and-gmc-trucks

[hatzie]

The 1991 Suburban DRAC is on the passenger side near the engine ECU. Download the 1991 RV-P wiring diagrams... Fig 41 is Suburban Figs 54 & 55 are RV trucks.


Before you start modifying the cluster to fit the tach get the whole un-modified panel operating in your truck. That way you are only dealing with hooking up the new fuel gauge and tach when you install the GMSPORTS replacement.

The only electronic gauge in the 90-91 Suburban clusters is the speedometer. The VSS signal from the DRAC comes in on the Instrument panel connector terminal 18...

You have a short chunk of the original harness still attached. Keep it as a reference as you re-pin your truck... You may need to liberate a few terminals for the VSS signal and Check engine lamps after you get the basic lights and analog gauges working.

The rest of the gauges are analog movements just like the 73-89 clusters.

Before you start moving terminals. Be aware... The 73-89 instrument panel plugs have more than one ground and ignition power wire depending on the year.
Your new 1991 cluster only has one IGN power and one ground. This means you are going to have a extra ground and IGN power wires that will have to be protected with heatshrink to keep from shorting the cab harness out.
I would take a notepad and write down each wire color, connector-cavity #, and Circuit # that you are moving and to what connector-cavity # you are moving it.
The other thing I would do is label each wire in your instrument panel plug with the GM circuit # using masking tape and a sharpie.

The attached Wiring Page is from the 1990 manual 1991 Suburban cluster is pinned the same... You will need to download the wiring diagrams for your year as well...

Circuit # cheat sheet for connector # 8900371 on the below page.
8 Panel illumination (comes on with parking & head lights)
11 Hi Beam lamp
14 LH Turn Indicator
15 RH Turn Indicator
25 Voltmeter
30 Fuel gauge
31 Oil pressure gauge
33 Brake warning lamp
35 Temp gauge
39 Ignition Power
69 Low Coolant Lamp
150 Ground
237 Seatbelt Lamp
419 Check-Engine lamp from ECU
824 DRAC VSS
592 DRL (Canada)
629 DRL (Canada)

[slimneverdies]

Originally Posted by hatzie

The 1991 Suburban DRAC is on the passenger side near the engine ECU. Download the 1991 RV-P wiring diagrams... Fig 41 is Suburban Figs 54 & 55 are RV trucks.


Before you start modifying the cluster to fit the tach get the whole un-modified panel operating in your truck. That way you are only dealing with hooking up the new fuel gauge and tach when you install the GMSPORTS replacement.

The only electronic gauge in the 90-91 Suburban clusters is the speedometer. The VSS signal from the DRAC comes in on the Instrument panel connector terminal 18...

You have a short chunk of the original harness still attached. Keep it as a reference as you re-pin your truck... You may need to liberate a few terminals for the VSS signal and Check engine lamps after you get the basic lights and analog gauges working.

The rest of the gauges are analog movements just like the 73-89 clusters.

Before you start moving terminals. Be aware... The 73-89 instrument panel plugs have more than one ground and ignition power wire depending on the year.
Your new 1991 cluster only has one IGN power and one ground. This means you are going to have a extra ground and IGN power wires that will have to be protected with heatshrink to keep from shorting the cab harness out.
I would take a notepad and write down each wire color, connector-cavity #, and Circuit # that you are moving and to what connector-cavity # you are moving it.
The other thing I would do is label each wire in your instrument panel plug with the GM circuit # using masking tape and a sharpie.

The attached Wiring Page is from the 1990 manual 1991 Suburban cluster is pinned the same... You will need to download the wiring diagrams for your year as well...

Circuit # cheat sheet for connector # 8900371 on the below page.
8 Panel illumination (comes on with parking & head lights)
11 Hi Beam lamp
14 LH Turn Indicator
15 RH Turn Indicator
25 Voltmeter
30 Fuel gauge
31 Oil pressure gauge
33 Brake warning lamp
35 Temp gauge
39 Ignition Power
69 Low Coolant Lamp
150 Ground
237 Seatbelt Lamp
419 Check-Engine lamp from ECU
824 DRAC VSS
592 DRL (Canada)
629 DRL (Canada)

Sheez. No one said it was simple. I think I'm going to have to wait till the weekend to tackle this. I don't want to short anything out. I definitely will install the cluster to verify that it works before I start to upgrade it. I see you have all the manuals and that helps a bunch too

Thanks
Slim

[hatzie]

I probably don't need to say this but I will anyway. The 1991 Instrument panel plug pinout is very different from the earlier completely analog gauge panel plug so don't just plug it in...

[slimneverdies]

Originally Posted by hatzie

I probably don't need to say this but I will anyway. The 1991 Instrument panel plug pinout is very different from the earlier completely analog gauge panel plug so don't just plug it in...

Yeah, I can see that just by looking at the back of them both.

[72MARIO]

Is there any need for the drac when using the tci controller ? Does the tci controller have a plug and 2 wires that simply connect to the 1990-91 speedometer ?

[slimneverdies]

Originally Posted by 72MARIO

Is there any need for the drac when using the tci controller ? Does the tci controller have a plug and 2 wires that simply connect to the 1990-91 speedometer ?

That would be great if it's that easy. I'm looking thru the manual from tci and it doesn't clearly state what's needed outside of the system for the electric speedo

[hatzie]

You only need one wire the speedo uses the vehicle ground.
I'd guess the EZ-TCU has a programmable VSS output.

[slimneverdies]

I called TCI amd I was told the Ez-tcu can be plugged straight into the gauge if you have a ppm sensor signal or direct VSS connection and you just set the unit to 16K.

Also I wasn't aware what needs to be done to fit another gauge(GM sport tac) in the cluster. I found this thread. Maybe I'm missing something
http://67-72chevytrucks.com/vboard/s...d.php?t=265731

[hatzie]

That looks like they are installing the GM big truck tachs. Here's a thread that shows how the "GM Sport Salvage" tach was installed in an earlier instrument bucket.
http://67-72chevytrucks.com/vboard/s...d.php?t=470240

[Rascal_one2001]

The speedo gets power and ground from shared points in the printed circuit board with the ez tcu you have one wire that can go strait to the speedo signal but you must re organize your harness wires to use the complete cluster. You don't need the drac with ez tcu it has all the calibration digital thru your hand held.

[slimneverdies]

Originally Posted by hatzie

That looks like they are installing the GM big truck tachs. Here's a thread that shows how the "GM Sport Salvage" tach was installed in an earlier instrument bucket.
http://67-72chevytrucks.com/vboard/s...d.php?t=470240

Ok. This makes more sense to me for sure. Thanks

Originally Posted by Rascal_one2001

The speedo gets power and ground from shared points in the printed circuit board with the ez tcu you have one wire that can go strait to the speedo signal but you must re organize your harness wires to use the complete cluster. You don't need the drac with ez tcu it has all the calibration digital thru your hand held.

Do you have any better pics of your repinning? Couldn't I just look at where all the wires are coming from in the back of the 78 cluster and tie them into the new harness with the corresponding pin?

[hatzie]

Originally Posted by slimneverdies

Do you have any better pics of your repinning? Couldn't I just look at where all the wires are coming from in the back of the 78 cluster and tie them into the new harness with the corresponding pin?

Download the wiring diagram for your year truck and the 1991 diagrams. Print the page with the instrument cluster.
Print the 1991 page image I uploaded from the 1991 diagrams or find the same page in the 1991 diagrams and print it...
The main GM circuit numbers don't change much from year to year so you can build a cheatsheet on paper using the circuit numbers. 1991 will have a few high number circuits > 300, for example the VSS to the speedo #824 and the Check Engine Light #419, that are not present on most of the earlier trucks. CEL is present starting in 1987 but will be in a different position on the Instrument Cluuster plug.