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Hello,
Looking for someone to please help me with an electrical gremlin.
Over the last 2 months I have had 3 times when the car dies while driving and wont start again without waiting about an hour. I replaced the battery and performed a parasitic drain test on the alternator. All good.
Yesterday I was towed home. This time instead of starting back up after waiting an hour I ran into something new. When I turn the key on it takes about 5-8 seconds for the instrument cluster to move the gauges except all gauges go to 0.I have lost communication with all modules and cant even pull the codes.
I checked battery voltage at battery, 12.43 volts. I pulled all BCM and PCM fuses and checked with ohm meter as well as under hood fuses.
I pulled the short bar from start connector with 4 wires to isolate the PCM and BCM.....still nothing.
I cleaned the grounds with a dremel and applied new conductive grease. The grounds I cleaned were the one next to the battery , 1 on each side of the car by the headlights and another on the driver side block that has a strap attached. Still nothing
PCM and BCM are bone dry, no water at all.
Please help!!!!!! What else can it be. IThe only thing I havent checked is the starter connections and the PCM connections......before I start on that can anyone maybe share their similar experience?
If you can’t communicate with any modules you may have an issue with your Class 2 serial data line...I’m assuming you’re using a scan tool. The BCM and PCM should be on the other splice pack (Star Connector)...pull that “comb” off too...now see if the modules come back on line...you have to jump the dark green and light green wires to each other (PCM to BCM)...now see if the car will start !!...for the DIY’er without a breakout box and a scope this is about as much as you can do !!
I will try that in the morning . Got called into work this evening. Thank you so much for the reply. If this works, would the issue be in the connector or in the BCM?
If your car starts one of the modules on that star connector is causing havoc on the serial data line...whether it’s a short to power or to ground. The serial data line is how the modules talk to one another...think of it as all the modules are on a conference call...one idiot is talking over everyone else on the data line so now the HVAC can’t talk or receive info from the BCM.
The serial data line produces a 0-7 volt square wave which a multimeter is just to slow to read accurately...that’s why a scope is required to quickly diagnose this problem...if the problem is on that star connector basically it comes down to removing that particular module...one of 9 on that star connector !!..this is what that data line voltage looks like on my ‘01 !!
Thanks to C5 DIAG I am back up and running.!!!!! Had a bad connection in the star #2 connector. Last pins on both sides were corroded . After jumping BCM to PCM she fired up. Cleaned out connector and all is up with not 1 code except that I dont run a MAF.
C5 DIAG is the reason this forum works and I cant thank you enough.
Corvette dies sometimes while driving
