I have a 2002 Z06. I recently had a LS3 put in it that had the proper reluctor wheel and trigger put in it along with the several required wiring adapters. I am now getting no signal from the PCM.

Symptoms:
When you turn the key on there are a lot of error messages about active handling, low fuel, reduced power, etc. The fuel pump also does not prime. Car will turn over but shows no signs of firing up.

More Info:
Engine was just swapped in and this problem happened. Car has not ran since the engine swap. They noticed a loose ground strap on the drive side just hanging and placed it between the header flange and head. The car then found the PCM and fuel pump turned on. I got the car home and could no replicate this. I also attempted to attach the ground strap to the engine block and still no luck.

What are common causes of this? Where should I start?

I was planning to send the PCM off to Vengeance Racing for a base tune, if it is bad would they be able to determine this when the connect to it?

Thanks in advance!

 

Got some more info on the car. I currently have the driver side seat and frame removed. I also have the passenger side window switch unplugged.

I get the "reduced power" "low fuel" and other warnings. Temp gauge is pegged and fuel gauge is on empty. Fuel pump will not turn on.

The car will either not connect to and of the modules in troubleshoot mode, or will connect to all except the PCM (and SCM from seat of course)


Car finally cooperated to pull the codes and gave these:

PCM - No Comm
SCM - No Comm (seat missing)

Codes I got before clearing them out:

TCS
U1301 H
C1214 HC
C1233 HC
C1276 H
C1288 H
C1295 H
C1296 HC
U1000 HC
U1016 H


BCM
U1255 HC
U1096 H


SDM
B0026 HC
B0090 H
U1000 HC
U1301 H
U1016 HC
U1040 H
U1096 H
U1064 H


IPC
U1255 H
U1040 H
U1160 H
U1088 H
U1176 H


RADIO
U1096 H


HVAC
U1064 H
U1096 H
U1160 H
U1255 H
B0338 H (interior temp sensor is unplugged)


LDAC
B2202 H
B2282 H
B2284 H
U1255 H
U1064 H
U1016 H
U1096 H


RDCM
B2283 H
B2285 H
B2265 H
U1255 H
U1064 H
U1016 H
U1096 H


RFA
U1000 HC
U1255 H
U1064 H
U1096 H
U1016 H


I then reset all codes and these codes instantly reappeared:

TCS
C1214 HC
C1233 HC


BCM
U1255 HC


SDM
B0026 HC


HVAC
B0338 HC (interior temp sensor is unplugged)


RDCM
NO COMM


Then the car was turned over (no starting of course) and these were the codes:
(all of the previous hard set ones also included here but not listed)

TCS
U1296 HC
U1000 HC


SDM
U1000 HC
U1016 HC


RDCM
NO CODES (reconnected at least!)

RFA
U1000 HC


Also, the fuel pump has primed a time or two. Not sure what caused this. I heard it one time, let the pressure out and never heard it again. It had pressure but it could just be from the fuel heating up in the tank.

 

I added a lot of info, maybe this will give a better idea to some of you experts on here as to where to point me.

I also cleaned the two black box grounds (were pretty clean to begin with, but scrubbed everything good and clean)

I also unplugged the 4 wire connector by the BCM and still no start from the car

 

Check your grounds and your fuses
G105 On left bottom of engine. See Fig. 1 .
G106 On right side of engine, above starter.
G107 At top left rear of engine. See Fig. 2 .

 

You should have THREE ground points on the engine.

1. G-107 on the back of the drivers side head.
2. G-106 Above the starter on the engine block. The battery ground wire attaches there and you should also have a single wire with an eyelet on that ground point

3. G-105 Drivers side of the engine block above the oilfilter housing on the block. There should be a single wire and a braded ground strap attached to the block.

Here is a picture of G-106 above the starter:



Here is a picture of G-107 behind the head:

 

Will g105 always have a single wire and a braided ground? i only remember seeing the braided ground on my 2002 c5.... i wonder if thats why it wont stay running

 

I only see the one large wire going into the ground above the starter, where is the small wire and is this important to having the PCM function?

 

I believe there should be a small black with white stripe or a gray one going to that ground as well. It's probably important

 

If it wasnt needed,,,,,,,, why would GM put it there.......???

YES.... Its the PCM GROUND WIRE. I guess its needed.

Car will NOT run without it.

 

Strange thing is that I tried to find it and it isn't there. I guess this is why it isn't attached. Ill go look one more time for it otherwise it might be going back to the place that put the engine in to have something done.

Man it sure it hard to fit my hands down in there to look for it!

Is it inside of a larger harness? Does it go straight to the PCM? Any tips on tracking it down?

 

Look at the picture with the starter and G-106. The harness that is laying on top of the starter has the GROUND WIRE exiting from it right where it splits into the smaller harnesses. I see them broke off inside the main harness all the time.

Some times I see people attach the ground wire to the starter POSITIVE terminal. That makes all sorts of really cool craze stuff happen.

You might want to look at the solenoid and make sure that you are not one of those unfortunate people

Bill

 

Found it, they had it tucked and hidden behind the harness. I finally got both wires connected and SUCCESS!!

Car is attempting to fire over, fuel pump works and the PCM is finally being seen. Amazing what one little wire did.


Now to mail off the ECU for a base tune to help with the huge injectors and other parts changes. Hopefully I will have some exhaust sounds on here in the next few weeks.


Thanks again for all of the help!

 

Our computer in the C5 is refered to as the Power Train Control Module (PCM) In the C6 they changed it to ECU

If you have larger injectors, its a wonder it runs. The Tuner has to change the injector size in the PCM. Your new injsctors should have come with a data sheed. On it is a lot of tuning data that the tuner will need to properly tune the injector data.

Bill

 

If you have your old injectors, reinstall then until you get to the tuner and then reinstall the larger injectors. Your engine doesnt need the larger injectors during closed loop cruise.

 

It has a stock LS3 intake, rails and injectors. The LS6 injectors it came with won't easily fit back in there. PCM is already in the mail anyway so hopefully I will be driving the car next week.

Thanks again for the help!