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Hi everyone,
I was wondering where the grounds for the PCM and EBCM are located. Do they share the same ground, or, are grounded at different locations? The question stems from the communication issue between the PCM and EBCM - codes PCM P1571 and TCS C 1277 They are my last codes to clear on the car.
Thanks
Yellow '01
I personally doubt grounds are the cause for the two codes. JMHO
There is a dedicated wire pair between the PCM and the EBCM that carries the signaling for torque. I would look at the possibility of acid spillage onto the PCM from a now or previously leaking battery and also at the wiring to the EBCM connector. Wires in question are orange/black and tan/black. I'll try to post the wiring diagram.
8VETTE7
Your the MAN!! This is exactly what I needed to get a good start on the diagnostics. I concur with you on the grounds as the ABS has no problems and the PCM has no issues as well. I have cleaned and inspected all the grounds. I just wanted to be sure I had not missed anything. Since its a Comm problem, there is a great chance it could be that pair of wires. Will pin this out and inspect all the connections, especially the twisted pair you mentioned. I'm also sending the PCM out to the West coast guys this week for a few tweeks so I'll be right in the heart of it this weekend. I'll give an update probably mid week or so as I'm starting this process tomorrow. Anything else you might advise me to look for or explore there, I'm tuned in.
THANKS!!
Yellow '01
I personally doubt grounds are the cause for the two codes. JMHO
There is a dedicated wire pair between the PCM and the EBCM that carries the signaling for torque. I would look at the possibility of acid spillage onto the PCM from a now or previously leaking battery and also at the wiring to the EBCM connector. Wires in question are orange/black and tan/black. I'll try to post the wiring diagram.
8VETTE7
Got into the PCM area and found two things I was needing your expertise on. There is a black box that is attached to the PCM holding bracket. It has two multiple connection connectors coming off it. I pulled it first then the holding bracket and took the PCM out. I was wondering which module it is.
Second, directly above the PCM and below the battery box/platform is a ten pin black connector clipped to the body/frame. The wires going to the connector have a PINK piece of rubber like wrap on them. What is that connector for? If you need a picture I can get one sent. Found LOTS of dirt on these items, no acidic corrosion though. Makes you wonder what the engineers where thinking.....
Thanks
Yellow '01
I don't know what the second item is from the description. A picture might help....
Dirt is to be expected given the location but acid from the battery is often the cause of problems. The side post batteries used on the 97 - 2003 C5 were well known for leaking acid down onto the wiring etc directly below the battery. GM changed the 2004 back to the traditional top post batteries. I wonder why???
Maybe making it easier to reconnect connections. The side post was designed to seal off atmospheric moisture and stop parasitic draw from damp top battery surfaces - makes you wonder what their thinking. The TAC is spot-on as I looked at one on-line this evening and it looks exactly the same. I always wondered where that was mounted.... Anyway, I'll get you the pic of that connector on Saturday. Tomorrow I'm going parts hunting.
Yellow '01
Last edited by Yellow '01; Jul 1, 2016 at 12:28 AM.
Reason: More Info
8VETTE7
The tan and orange wires tested good, great continuity and pin condition. .001 ohms
The pictures included in this reply is of the connector I am not recognizing. At this point, I am not sure as to what to do further except put the ECM back in after I get it back from East Coast Superchargers and hope for the best
8VETTE7
Thanks for your dedication. No rush and ENJOY THE 4th!!!! I am sending Chris @ ECS the test results of these 2 wires and have him look close at these areas pf the PCM.
Again, THANKS for your guidance,
Yellow '01
8VETTE7
It matches perfect. This will help me make sure these pins have the correct voltages/ground continuities. Got off the phone with Doug at ECSuperchargers, he said he will closely check this circuit within the PCM while he is working his magic. THANKS for the help on this and I will update this thread with the outcome as soon as I can.
Yellow '01
Grounds for PCM and EBCM
