V1 You Guessed It - An Electrical Issue

[G-Quest]

Hello all, Ken here, #268 ext. city, 2006 SS/SC with several electrical questions. The donor was alive and well before disassembly – I put about 5,000 miles on it waiting for COVID pass us by.

After assembling the Goblin I plugged in the battery and found that I, at best, scored a C- in wiring.
Things that worked:
* Lights – High/Low beams, turn signals, running lights, dash lights
* Horn
* Intercooler fan
* Several dash indicator lights (MIL, security)
* Throttle body butterfly
* Starter (will spin the engine whether the clutch is in or out)

Things that didn’t work:
* No gage responses
* Wouldn’t start
* Couldn’t get the fuel pump to prime

Tried to throw my old HF code reader on the OBDII and it wouldn’t connect. So, what’s a guy to do – search the DF Forum, of course.

I, like several others, (I’ve since discovered) went a little overboard when following instructions on the wiring video to solder all of the dark green (GMLAN) wires together and ended up with continuity between pin 1 and 2 on the ODBII connector. Seeing that, I thought I should look more closely at all of the info networks to make sure there were no other goofs.

After pouring over the schematics on Alldatadiy (bless you @Ross) I’ve put together what I believe to be the connections for the 2006 SS/SC GMLANs. If anyone out there more skilled in the electrical arts could take a look and see if I’m on the right track I would appreciate it.

I found the wire for BCM / C2 / Pin 38 cut when looking around. I don’t have a digital radio and I’m not sure what a VCIM is or whether it still exists so I’m not sure if I need to reconnect the wire or not. Other data circuits:

After verifying the above connectivity there were only a few changes in the win/loss categories - I did get the reader to throw a fuel system code. No gauges, no gas, no starting.

Now the questions:

* Does the above look correct? Any modifications, deletions, additions or suggestions (e.g. take up knitting instead of building a Goblin)?

I think I may have fried something in the fuse box when trying to jump the fuel pump the second time. I did verify +12v coming up to the relay connection and continuity between the fuel pump power supply wire (pin B) and the power feed wire in the fuse block (connector C2 pin D4) but no joy in getting voltage through the relay to the pump for the key-on prime.

* Can anyone share with me the steps to disassemble the fuse box and inspect/repair the little devil? At first glance it doesn’t look like it wants to come apart easily.

* Has anyone developed a “continuity checklist” similar to the above tables for the Goblin harness modifications? Looking back I would have gladly spent a couple of hours with the harness on the table checking my work vs. diagnosing issues in the car.

If there are no easy fixes I'll probably yank the harness back out and step-by-step verify continuity of all harness mods. Yikes – knitting isn’t sounding so bad…

 

[Ross]

VCIM = Vehicle Communications Interface Module is kind of like your GM vehicle's cell phone. For OnStar-equipped vehicles, but removed from our Goblins.

 

[OptimizePrime]

Do you have your power steering plugged in?

The fuse box top is just a bunch of tabs, just make sure not to break them as you flex and pull up on each of them as you wiggle it off. Once you have the top off, make sure the plugs are well seated. The bolts that synch the plugs together needs to be pretty tight.

 

[Gtstorey]

Here is a link with more info on how the GMLAN works. Page 2-3 describes how to check continuity on the High Speed GLAN and the resistance it should see.
SECTION ‘X’ CONTENTS (aeswave.com)

 

[Lonny]

Pin number 2 on the OBDII should have a green wire that goes and the way back to the ECM. I don't remember off hand which pin number. Make sure you have it connected.

 

[G-Quest]

Thanks to all for your comments:

@Ross - do you think there is any harm in leaving the the connection to the radio/VICM disconnected (BCM / C2 / Pin 38) or should I wire it to the splice even though there is nothing feeding into it?

@Optimize - I had all the connectors attached during the first start trials (except for the TPMS/fob receiver - I seem to have misplaced it at some point). I've read of several builders with the fuel pump/fuse box problem that said they disassembled the actual fuse box (the part that holds all of the relays and fuses) as opposed to the fuse block that contains all of the main harness connectors. When I look at the fuse box - the part with 7mm bolts sticking through it - I'm not seeing an easy route to open it up to check for opens or shorts. I may be misunderstanding where the problems are being found.

@Gtstorey - Thanks for the link - very interesting. I will check it out this weekend.

@Lonny - You are right, that was the first mistake. I had both the ODBII Pin 2 and (in my case - the PCM / C1 / Pin 16) both going to the low speed splice. I've since backed them off and connected them together as shown above. The positive result was that my code reader now functions on the OBDII port. Does the list of splice connections shown above look correct to you?

I'm certain you could re-wire a Goblin harness by sense of smell but do you have a cheat-sheet regarding the modifications? I was going to try to use the wire labels DF supplies and just do a pin-to-pin continuity test.

 

[Gtstorey]

If you are going to do a pin to pin check, get an all data subscription so you have the full wiring diagrams and circuit list. For the most part it’s pretty obvious which circuits are required.

 

[Ross]

Ken, there is no point in wiring the green low speed wire to the VCIM, unless you are equiping your Goblin with OnStar.
Maybe that would be fun.

Hello OnStar, my doors and windows are all missing.
Oh that is terrible, let me look into it. I see you are missing the safety restraint system and emission too. I will send a tow vehicle. Were you in an accident? Are you okay?