Crusty Rusty Leaky Squeaky 67 Step

[rustytruck50]

That's always a great feeling to get past a major bump in the road...so sweetens the finished product!

[Jason7121]

Had to use the pull up resistor with my classic instruments as well. Have you calibrated speedo and put it in learn mode yet?

[Elliot949]

What you are experiencing is exactly why I stay old school... I would have burnt the truck to the ground long ago... LOL

[Vic1947]

Originally Posted by Xeen

Cobbling together a patchwork of components from several different manufactures can be tricky and time consuming even if you have experience and for the guys that don't do this kind of stuff all the time it is a daunting challenge but you are smart and determined and you will get through it, hell you already solved one tricky problem and you just started working on it, you will have it working properly before you know it.

Thanks, Brian.

Originally Posted by rustytruck50

That's always a great feeling to get past a major bump in the road...so sweetens the finished product!

So true, and this was a biggie.

Originally Posted by Jason7121

Had to use the pull up resistor with my classic instruments as well. Have you calibrated speedo and put it in learn mode yet?

I'm still not getting the speedo signal to the SN74Z box for some reason, Jason. It has power and the green LED is on, but the manual says if it doesn't blink, there's a problem with the signal. I used a patch cable to bypass the other devices and directly connect the SPEEDOUT cable to the SPEEDO IN terminal on the box, but no luck. I have a handheld oscilloscope ordered off eBay, since that's the only way (I know of) to verify the signal. Tomorrow I'm going to hook the laptop to the diagnostic cable for the transmission, fire up the software that came with the C&C package and see if it will talk to the TCU. Maybe something will stick out. The guys at Classic said it would be best to use the ECU signal (speedout) versus the VSS +/- input. Best I can tell, the single wire is a square wave and the two wire input is a sine wave. Only difference on the SN74Z (aside from the terminals used) is the filter switch. Off for square wave, on for sine wave. If I'm unable to sort it out with the software, I'll make another run at CI's customer service.

Originally Posted by Elliot949

What you are experiencing is exactly why I stay old school... I would have burnt the truck to the ground long ago... LOL

Ain't that the truth, Dan. If I'd left the Gen1 SBC in it, I'd be out doing donuts right now.

I did get a few things done today. Re-bled the brakes, topped off rear end lube and trans fluid plus I got the Kamikaze charcoal filter mounted and hooked to the newly installed vent tube. I think I'm safe from any tank pressurization issues now. As you can see from the photo below, it looks like a bomb went off in my recently completed interior.

[Jason7121]

I used the single vss output from the ecm to the sn74 box. I will look at my setup again and see if I can help in anyway.

[Jason7121]

Far as I can tell I have a single computer speed signal going to the sn74z speedo in terminal. Switches 1-5 off on the sn74z on the back of speedo switches 5,6,7,8 open. I used the marked mile method and according to GPS it's right on the money. According to my notes I called Classic instruments and that's what they told me to do. Gm uses 16,000 ppm for speedo.

[Vic1947]

Originally Posted by Jason7121

Far as I can tell I have a single computer speed signal going to the sn74z speedo in terminal. Switches 1-5 off on the sn74z on the back of speedo switches 5,6,7,8 open. I used the marked mile method and according to GPS it's right on the money. According to my notes I called Classic instruments and that's what they told me to do. Gm uses 16,000 ppm for speedo.

Thanks, Jason. From what I can find online, I think several things are going on.
1. There's an orange wire coming out of the GMPP harness marked SPEEDOUT that's coming from the TCU. It is what I currently have connected to the SPEEDO IN terminal on the SN74Z with switch settings as you described.
2. There's a brown wire (circuit 818) that passes thru the 12 pin bulkhead connector that is supposed to be Vehicle Speed - Out. The I-sheet states it is a non-scaled output for use with auto-scaling speedometers and will not function unless a vehicle speed sensor is connected to the ECM thru the VSS wire in the harness. This is the wire the GMPP help desk tech referenced in our conversation Friday when discussing the inoperative speedo. However, as far as I can tell, there's no non-terminated wire in the harness that ties back to it.
3. Again, as best I can tell, the plug marked VEH SPD is meant to accept a sine wave that varies between 0-5V. The I-sheet states it's optional and not needed for engine operation... which is true to a point. But, apparently, without it there may be idle and stalling problems per this article. While it may ultimately be a driveability, fuel mileage issue, I don't think it's relevant to the speedo not working.

So with all that, do you recall the wire color coming out of your harness that goes to the speedo in on the SN74Z? If your setup is like mine, the harness wire is too short to make the trip and had to be spliced.

[Jason7121]

I modified a stock factory wire harness myself. The wire color was white. What year computer ecm does your kit have I can look at pin out ok gm site. I am a tech at gm dealer so I have access to schematics pin out etc.

[Jason7121]

I would think the wire that was labeled speed out on your harness would be the one to go to sn74

[Ol Blue K20]

This is above my head. Probably what's kept me from doing this swap. I'm not only old but old school......good luck Vic

[Vic1947]

Originally Posted by Jason7121

I modified a stock factory wire harness myself. The wire color was white. What year computer ecm does your kit have I can look at pin out ok gm site. I am a tech at gm dealer so I have access to schematics pin out etc.

The harness I'm using is the one supplied by GM for their Connect & Cruise crate setups. Mine is a 430HP LS3 and 4l65e Supermatic transmission. My understanding is that it's basically a 2010 Camaro setup with a harness modified to eliminate most non essential functions and work with a 19258270 controller.

Originally Posted by Jason7121

I would think the wire that was labeled speed out on your harness would be the one to go to sn74

I agree and that's also what the tech at Classic Instruments said. But with it hooked up that way, when I place the trans in drive and let the tires rotate (on jackstands) the speedo is dead as a door nail. I don't think you should have to do any of the three calibration methods for the dial to at least indicate something... even it it's wrong. Do you recall if yours worked right out of the gate or did you calibrate to get it going?

BTW, thanks a ton for the help, Jason.

[Jason7121]

How fast are spinning the wheels mine wouldn't register at first until I got over 30 mph

[Vic1947]

The 4L65E came with a thumb drive that had a calibration software installation package and a USB laptop cable. I plugged the cable into my laptop this afternoon and turned the ignition switch to on and the TCU loaded the cal file into the application. When I started the engine, it displayed various pieces of info such as RPM, line pressure, coolant temp, volts, trans temp, throttle position, gear selection and speed. However, when I placed it in gear and let the tires rotate, the virtual speedometer on the screen didn't display the speed like I figured it would. So something is out of whack. Could be related to not having the optional VSS input hooked up, don't know. I'll call the GM hotline again tomorrow with my case number and see if they can better assist me now that I have more details.

[Vic1947]

Originally Posted by Jason7121

How fast are spinning the wheels mine wouldn't register at first until I got over 30 mph

Probably not 30 mph. Just off idle a little bit. I'll go see what it does with more tire speed.

[Vic1947]

No luck... still no readout. At this point, if I had to guess, I'd say there's a problem with the signal coming out of the TCU but I won't really know until I get a scope on it later this week. I have some other stuff to do to keep me occupied, but the not knowing is killing me.

[Vic1947]

Originally Posted by Ol Blue K20

This is above my head. Probably what's kept me from doing this swap. I'm not only old but old school......good luck Vic

Thanks, Dale, I know what you mean. The younger guys take to it like a duck to water, but at my age, an HEI is high tech, baby!

[Jason7121]

No matter if speedo works or not you should be able to read vehicle speed with a scanner the two wire vss on back of tailshaft should be prewired with your harness I would think.

[Vic1947]

Originally Posted by Jason7121

No matter if speedo works or not you should be able to read vehicle speed with a scanner the two wire vss on back of tailshaft should be prewired with your harness I would think.

Yep, it's there. I'm waiting on an OBDII scanner doohickey I ordered last week, so I'm not able to check anything at this time. I am a bit confused, though, as to why the laptop transmission calibration software app didn't display the speed but everything else worked. It looks like the app is meant to allow you to modify rear gear ratio and tire size for an OEM speedo and maybe even tweak the shift points but not much else. That said though, you'd think it keys off the same VSS info that would be accessed via the OBDII port.

[knomadd]

Vic, You may need to test that speed signal sending unit (whatever it's called) to see if it's even operational. I know it's new, but you know as well as I do, even some new parts are dead right out of the box. It sounds to me like you either have a dead sensor/sending unit, or a signal wire that's not hooked up correctly.

I'd think the trans software would show you the speed too, otherwise what good is it to be able to log data and see what it's doing before just blindly changing settings?

[Vic1947]

Originally Posted by knomadd

Vic, You may need to test that speed signal sending unit (whatever it's called) to see if it's even operational. I know it's new, but you know as well as I do, even some new parts are dead right out of the box. It sounds to me like you either have a dead sensor/sending unit, or a signal wire that's not hooked up correctly.

I'd think the trans software would show you the speed too, otherwise what good is it to be able to log data and see what it's doing before just blindly changing settings?

I was thinking along the same lines, Duane. I called the GM Powertrain hotline this afternoon and discussed it with a tech. He said I should see a 1-3VAC signal right out of the sensor with the tires rotating. I need to get something rigged up where I can safely measure the sensor voltage with the truck in gear. Those pins on the sender are tiny!

The tech said if the sender was good, I need to hook a scanner to the OBDII port to see if the signal is making it to the ECU. It goes from the sender to the ECU and from there to the TCU. So if it makes it to the ECU and is readable at the diagnostic port, then I need to find out if it's getting in (and out of) the TCU. For that, I'll have to use the oscilloscope I have on order and don't have yet.

The tech was reluctantly helpful today. He said they were not really supposed to help consumers with diagnostics due to liability issues. But he gave me enough info to get me going.

[Low Elco]

Please tell me more of this Kamikaze charcoal vent of which you speak.

[Vic1947]

Originally Posted by Low Elco

Please tell me more of this Kamikaze charcoal vent of which you speak.

I was looking for a charcoal canister to connect to the vent on the gas tank when I ran across several listings on eBay for Kawasaki Ninja scoots. The size and shape looked easy to adapt to my needs, so I bought one that was a take off from a relatively new bike. I'm guessing bike builders remove them during the customization process. Mine came with an electric shutoff solenoid, so if you wanted, you could wire it to completely close the vent when the truck isn't running. Plumbing it into the intake would be the most effective, but I was mainly looking to neutralize any vapors coming from the vent. I'll try it like this and if I notice any fuel smell in the shop after filling up, I may hook up the shutoff solenoid.

[Low Elco]

Hrmnmn. I may have to investigate this. Thanks!

[AKC]

Vic, my hearty congratulations on the first fire-up of CRLS! Been a long time coming, you should be proud. And the missus' is to be commended for what must've been an exorbitant amount of patience!

Can't wait to see it all finished up.

But now I just feel like such a slacker...

[Vic1947]

Originally Posted by AKC

Vic, my hearty congratulations on the first fire-up of CRLS! Been a long time coming, you should be proud. And the missus' is to be commended for what must've been an exorbitant amount of patience!

Can't wait to see it all finished up.

But now I just feel like such a slacker...

Thanks, I appreciate it, and you're right that I owe a lot to Kathy. I was lucky in that way as she has always supported the drag racing and endless parade of projects over the years. Can't tell you how many times I've stored parts in the breakfast nook or rebuilt four speeds on the living room floor in the various places we've lived and she's never griped even once. Not all guys are that fortunate.

Brief update: I checked the VSS sender on the tailshaft today and it seems to be working. The tech at GM Powertrain said it should read 1-3 VAC, but it actually read between 1 and 13VAC. It might have gone even higher if I'd upped the speed some more, but at that point, I knew it was putting out a measurable signal. So I'll have to move on to the harness and modules. The scope finally arrived, but it was in pieces. Took me a while to assemble it, only to find that it needed to be setup first so I had to take it back apart since there was no provision in the case to access the calibration capacitors. Plus, I only had 6VDC power supplies and it needs 9V, so I have to make a parts run in the morning. Hopefully it won't take long to isolate the problem now that I have a double throwdown test gizmo.