Crusty Rusty Leaky Squeaky 67 Step

[Jason7121]

Good work Vic!

[rustytruck50]

Cool!!! Sounds great!!!

[knomadd]

Sounds great! Hopefully your issues are minor and easy to fix.

[Ol Blue K20]

Sounds great Vic.....

[builtbyKane]

What a milestone!!!

[Xeen]

I can't be the only one thinking this, when do we get to see the hood?
I've been dying to see it in paint.

[Vic1947]

Thanks, guys, for hanging in there with me. It's been a lot longer slog than I imagined. I know you understand how relieved I was that the engine actually fired up on the first try. It's a big step forward for a LS newbie. Certainly not as ambitious as some of you who've transplanted donor engines and had to jump thru even more hoops to make it all work, but still a big moment.

I spent a half hour on the phone yesterday with a GMPP tech and he was very helpful, although at the end of the call I still didn't really understand the difference between the VSS +/- and speedout wires. My BIL, Rick, and I had a long conversation about pull up - pull down resistors and after the call, I stumbled across a line in the Classic Instruments manual that stated the tachometer signal needs at least an 8V reference level and to use a 1K ohm resistor if the input wire is coming from a PCM/ECU. I only had about a dozen loose resistors in my electronics box, but luck was with me and I had one that was exactly 1K. After connecting it between switched 12DC and the signal post, I have a working tach.

Now it's on to the speedo. The GM tech seemed to think that having the NAV system and the cruise control piggybacked off the same wire going to the digital interface box for the speedo might be attenuating the signal. So today I'll patch a wire directly from the GMPP harness to the speedo box to delete the other two sinks temporarily. If that doesn't work, I'll be on the phone to Classic Instruments on Monday.

I still have some work to do in the engine compartment, so it will be a little bit before I get the hood on. It's been leaning up against the back of the shop gathering dust since I brought it home from paint.

[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.

[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

[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.

[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.

[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

[Jason7121]

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

[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!

[Aberdare]

Originally Posted by Vic1947

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!

Hey Vic:
Thought I'd chime in here after reading all the previous posts about your speedo function fault. Just a few quick questions to help you along the troubleshooting path.

1) Does your truck's new electronics include a Central Electronics Module (CEM)? -- or the equivalent as part of your electronics conversion installation.

2) Does your truck have an AFTER 1994 OBDII DATA LINK CONNECTOR? This will allow you to use a Diagnostics Scan Tool to troubleshoot the Data Stream information.

I have a background in Industrial Electronics and Automotive Electrical Systems... so with a little bit of information, I can point you in the right direction.

Cheers, Abe