ah.b.normal
Goblin Guru
Been there, done that.
Dan's #495 build (2006 SS/SC)
- Thread starter TheAnesthetist
- Start date
TheAnesthetist
Active Member
Those switches are on my list of things to check. The one at the end of the pedal travel is plugged in and the plunger depresses with the pedal. Seems unlikely that the switch went bad sitting in a box for the last couple months but certainly possible. Entirely possible that I messed up the wiring when I extended it but I followed the labelling and soldering pretty closely. I don't think that would explain the lack of voltage to the fuel pump though.
Traé
Well-Known Member
I too just found this issue in my harness as i was getting it in the car. You tied into the boost guage, have you had any issues? I had someone help me trace it back to the BCM grey connector on the back pin F3. I am going to try to trace it out and see if i accidently cut it during thinning.
TheAnesthetist
Active Member
I haven't touched the car in over a month. Got really fed up with it and decided we needed some time apart. I made a huge mistake trying to tackle this wiring harness myself. I don't have the patience for it and should have paid DF to do it.
TheAnesthetist
Active Member
Do you think thats an option? i just assumed they wouldnt be interested in trying to troubleshoot my harness.
TheAnesthetist
Active Member
Update: I continue to be baffled by my wiring issues. Turn the key on and I can hear some of the electronics come to life. The display says ENG POWER REDUCED. The fuel pump does not prime. Clutch in, turn the key to crank and I hear a relay in the BCM click but no response from the starter. I don't believe there's any issue with the clutch pedal sensors.
I pinned out and confirmed continuity on all of the high-speed GMLAN wires. No issues there, except I'm still getting 118 ohms across the data wires at the OBDii.
The security light on the cluster goes off after a couple seconds so I don't believe a key relearn will help.
I still think there's a grounding issue in the fuse box. I used my multimeter to trace the ground path for the PCM. It looks like its terminal ground is the lug next to the transmission on the left side of the car. I don't get any continuity between the lug and black wire on the engine-to-harness connector. I stripped the cover off the wire and used a jumper straight to a ground lug, still no change.
I also can't locate the common ground for all these relays. I see the CRANK/START and FUEL PUMP relays which could explain my problem.
I'm stumped here, guys.
I pinned out and confirmed continuity on all of the high-speed GMLAN wires. No issues there, except I'm still getting 118 ohms across the data wires at the OBDii.
The security light on the cluster goes off after a couple seconds so I don't believe a key relearn will help.
I still think there's a grounding issue in the fuse box. I used my multimeter to trace the ground path for the PCM. It looks like its terminal ground is the lug next to the transmission on the left side of the car. I don't get any continuity between the lug and black wire on the engine-to-harness connector. I stripped the cover off the wire and used a jumper straight to a ground lug, still no change.
I also can't locate the common ground for all these relays. I see the CRANK/START and FUEL PUMP relays which could explain my problem.
I'm stumped here, guys.
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TheAnesthetist
Active Member
Solved the fuel pump issue. Turns out I had the pump relay in the wrong spot. Now it primes with the key on
Edit: there are a couple of identical relays labeled CRANK or RUN/CRANK. Is it normal for these to get warm to the touch? I've swapped them around with each other and no change so I don't think any of the relays are bad. Also, the donor cobalt had no issues starting.
Edit: there are a couple of identical relays labeled CRANK or RUN/CRANK. Is it normal for these to get warm to the touch? I've swapped them around with each other and no change so I don't think any of the relays are bad. Also, the donor cobalt had no issues starting.
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Ross
Goblin Guru
Congrats on getting it started.
Is this issue still present? Have you pulled the OBDii codes?
TheAnesthetist
Active Member
Pulled the codes. Couple obvious EVAP codes and then there's p2128. Accelerator pedal position sensor 2 high voltage. Reading on some forums seems like that may mean a bad PCM?
Desert Sasqwatch
Goblin Guru
Or could be a ground or wiring. The throttle sensor runs off 5V I believe. If there is not a good ground it could be 12V trying to find ground and backfeeding through this circuit. Or a crossed up wire in the circuit with a 12V reference instead the 5V. Check your wiring and grounds before jumping into the purchase of another PCM.
Robinjo
Goblin Guru
I had a P2138 (similar to a P2128) Throttle Position/Pedal Correlation Issue that I couldn't track down for a long time. Tried new a new pedal, and new TB and a new jumper harness. Turned out it was the wiring that I ended up running a shielded wire. It's a common problem on the LSJ platform if you look in the Cobalt SS forums. It has happened to a couple here as well. I recommend that all LSJ's do this while the harness is on the table being worked as it's much easier then, but it got some pushback as not needed.
There is a test to see if it's the pedal embedded in this 4 page thread (below) about it all.
Full P2138 Thread
P2138 code and intermittent limp mode!
Hey guys my goblin has the 2008 LNF ss doner. recently when I have been driving around, my goblin has been intermittently going into limp mode. It can be a 2 min drive or a 15 min drive when it kicks in. I turn on the car and turn it back on, then it’s fine again for another 2min-15min. It’s...
Pedal Test Link
TheAnesthetist
Active Member
Another update. I ran a jumper wire from the battery directly to the connector on the clutch pedal sensor to trick it into thinking it had 12V and THE ENGINE CRANKED! Now I just have to figure out why none of these solid pink wires coming from the BCM have voltage. I'm getting some confusing results with my multimeter that I'm having trouble explaining with words. I'll try to shoot a video of what I've found.
TheAnesthetist
Active Member
That's a great idea. I'll work on that this evening. Heck, at this point I'd get it done as a tattoo if it would help lol
ah.b.normal
Goblin Guru
TheAnesthetist
Active Member
Great news. I solved the starting issue. To recap, I found that all of the solid pink wires that provide voltage to the sensors in the pedals were dead. Thanks to the always sage advice from @Gtstorey i dove into the wiring diagram. Turns out all of those circuits run through a single 10A fuse in the BCM. After banging my head against a wall for 2 months and nearly buying another donor just to harvest a fresh wiring harness, a blown fuse turned out to be the culprit. D'oh!
On to the next problem. I'm still getting a reduced engine power warning on the screen. Also still getting a p2128 code (Throttle/Pedal Position Sensor/Switch ‘E’ Circuit High). I used the info from @Robinjo to test the prongs on the accelerator pedal connector. Light blue is giving me 3.6V but I'm pretty sure it's supposed to be 0V. If I'm right, this would be the p2128 culprit. Also, the purple wire doesn't seem to be grounded.
Hopefully I can track down those gremlins and be back on track.
As always, thanks to you gurus for all your advice!
On to the next problem. I'm still getting a reduced engine power warning on the screen. Also still getting a p2128 code (Throttle/Pedal Position Sensor/Switch ‘E’ Circuit High). I used the info from @Robinjo to test the prongs on the accelerator pedal connector. Light blue is giving me 3.6V but I'm pretty sure it's supposed to be 0V. If I'm right, this would be the p2128 culprit. Also, the purple wire doesn't seem to be grounded.
As always, thanks to you gurus for all your advice!