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Hi Corvette world. I have a 1998 C5 convertible base model automatic 4 speed. I have a crank no start issue.
1. Turn key to on position
2. dim check engine light then regular dash lights and gauges cycle and illuminate then go off and then limp mode comes on with reduced power displaying and low fuel
3. I do not hear the fuel pump cycle and I have already tried jumper at fuse box to bypass fuse and pump does not prime. I have ran a line from battery to fuel pump and it works fine
4. car does crank over
5. Used onboard code reader. Everything says “No Comm”
6. Car was running fine. No rain sunny day. And I had just driver for an hour. I turned the car off and when I tried starting it 10 minutes later it had this issue
100,000 miles. Car ran amazing. It’s near mint condition with no leaks, engine bay looks new still. And interior is amazing still. I’m the original owner and have never driven this car wreckless and have had regular oil changes and inspections done at the dealership.
No comm problems could be as simple as bad electrical connection in the connectors between the car doors and car. There is a way to disconnect the various car modules that communicate with each other by pulling some electrical jumpers at the BCM and finding out which module is crashing the seriel data highway, A search on this forum will explain how to troubleshoot this problem.
I’ve tried searching the forum but I don’t find my issue. I find similar issues. I’m going to pull the battery and battery tray and clean the connections at the ECM and the other PCM on passenger floorboard and see if that helps. If I could just get a code or something that would be nice.
There is a panel you can remove on the passenger side wheel well to access the pcm, but you have to remove the wheel. The BCM is located in the passenger side footwell. Hopefully one of our resident experts can help you troubleshoot the no comm problem, one member recently had to replace the pcm to restore the no comms problem
Hi Corvette world. I have a 1998 C5 convertible base model automatic 4 speed. I have a crank no start issue.
1. Turn key to on position
2. dim check engine light then regular dash lights and gauges cycle and illuminate then go off and then limp mode comes on with reduced power displaying and low fuel
3. I do not hear the fuel pump cycle and I have already tried jumper at fuse box to bypass fuse and pump does not prime. I have ran a line from battery to fuel pump and it works fine
4. car does crank over
5. Used onboard code reader. Everything says “No Comm”
6. Car was running fine. No rain sunny day. And I had just driver for an hour. I turned the car off and when I tried starting it 10 minutes later it had this issue
100,000 miles. Car ran amazing. It’s near mint condition with no leaks, engine bay looks new still. And interior is amazing still. I’m the original owner and have never driven this car wreckless and have had regular oil changes and inspections done at the dealership.
please help me. I love this car.
With a “no comm” where you can’t communicate with any module locate the 2 splice pack connectors to the left of the BCM…remove the buss bar or “comb” as it’s called (in video) with the fewer wires and see if the car starts…if it does the problem is in one of those modules connected to that splice pack…if no luck reinstall the comb and remove the other one from the other splice pack…the car will not start unless you jumper the dark and light green wires (BCM to PCM)…if car starts the problem is one of the modules other than the BCM or PCM…if car doesn’t start with green wires jumped it’s either a bad BCM or PCM.
With a “no comm” where you can’t communicate with any module locate the 2 splice pack connectors to the left of the BCM…remove the buss bar or “comb” as it’s called (in video) with the fewer wires and see if the car starts…if it does the problem is in one of those modules connected to that splice pack…if no luck reinstall the comb and remove the other one from the other splice pack…the car will not start unless you jumper the dark and light green wires (BCM to PCM)…if car starts the problem is one of the modules other than the BCM or PCM…if car doesn’t start with green wires jumped it’s either a bad BCM or PCM.
Thanks for the input. But this is not exactly the issue I am having. When I turn the key to on the gauges cycle then it automatically goes into LIMP mode. The car will crank over but will not start. I do not hear the fuel pump prime and the ODBII says no comm on everything. Something has to be fried, either the ECM or PCM. Which one controls the fuel pump and spark????? Does anyone know where i can get mine refurbished or repaired? Ebay wants $600 for a used one.
The C5 has a BCM and the PCM, the PCM is located under the battery tray, it is the module that turns on the fuel pump as well as providing pulses to the fuel injectors and to the coil packs. Remove the left passenger wheel and remove the access cover on the inner fender liner and remove and inspect the connectors at the pcm. The pcm has been know to fail and cause the seriel data buss to crash causing lack of communication between all the modules.
There are a few businesses that specialize in repairs to automotive electronics modules out there simply do a internet search, and send them your module, they will test and repair your pcm if needed, more cost effective then buying another pcm.
No Comms to multiple modules The Dim CEL and NO Fuel pump prime kind of points me to a voltage issue. TRY THIS,, Its FREE.
Remove the close out panel from under the drivers side foot weel under the dash.
Locate the TWO large connectors that connect to the Ignition Switch.
Wiggle and twist those two connectors (ignition switch ON) and see if anything comes back to life.
If it does, you have bad female pins in the harness connectors. Specifically the four larger female pin connectors.
Just do that test and report back. If it is or is not a solution, we can go from there.
No Comms to multiple modules The Dim CEL and NO Fuel pump prime kind of points me to a voltage issue. TRY THIS,, Its FREE.
Remove the close out panel from under the drivers side foot weel under the dash.
Locate the TWO large connectors that connect to the Ignition Switch.
Wiggle and twist those two connectors (ignition switch ON) and see if anything comes back to life.
If it does, you have bad female pins in the harness connectors. Specifically the four larger female pin connectors.
Just do that test and report back. If it is or is not a solution, we can go from there.
Bill
.
I wiggled the wires still same issue. I removed the ECM under the battery tray. How can I test it to see if it’s fried
The C5 has a BCM and the PCM, the PCM is located under the battery tray, it is the module that turns on the fuel pump as well as providing pulses to the fuel injectors and to the coil packs. Remove the left passenger wheel and remove the access cover on the inner fender liner and remove and inspect the connectors at the pcm. The pcm has been know to fail and cause the seriel data buss to crash causing lack of communication between all the modules.
So I’ve removed these items pictured below. So is there anywhere I can take these to get tested
Passenger floorboard Under battery tray Under battery tray
Update to original post. Thank you to everyone who has responded. I’ve tried all of your suggestions and am down to these items pictured below as the issue. Can I test these at home somehow or can the dealership test them? Any other suggestions
You have to send those items to a business that specialize in testing and repairing automotive electronic modules, one of them is ABS fixer, or G7 Computers. Contact them and ship them your modules, they will test and repair if needed.
With a “no comm” where you can’t communicate with any module locate the 2 splice pack connectors to the left of the BCM…remove the buss bar or “comb” as it’s called (in video) with the fewer wires and see if the car starts…if it does the problem is in one of those modules connected to that splice pack…if no luck reinstall the comb and remove the other one from the other splice pack…the car will not start unless you jumper the dark and light green wires (BCM to PCM)…if car starts the problem is one of the modules other than the BCM or PCM…if car doesn’t start with green wires jumped it’s either a bad BCM or PCM.
can you calamity what unit is what. I’ll attach pictures. The book I have on this vehicle calls the ECM the (engine control module) the unit underneath the battery tray And the PCM (power train control module(the unit underneath the passenger side floorboard. But In this forum People are calling it PCM/BCM.
Also I hear a click almost sounding like a broken hard drive when I turn the key inside the box on passenger floorboard. Passenger floorboard Underneath battery tray
The ECM or PCM is located under the battery tray along with the TAC module. The BCM "body control module" is the module in the passenger footwell area, either module can fail and cause the no comms issue, have you removed the connectors on the PCM and inspected the pins and sockets for corrosion? The click you hear is probably the TDR which sits on top of the BCM, it sends power to energize the starter. I don't like how the PCM looks, it maybe the cause of your problems.
The ECM or PCM is located under the battery tray along with the TAC module. The BCM "body control module" is the module in the passenger footwell area, either module can fail and cause the no comms issue, have you removed the connectors on the PCM and inspected the pins and sockets for corrosion? The click you hear is probably the TDR which sits on top of the BCM, it sends power to energize the starter. I don't like how the PCM looks, it maybe the cause of your problems.
ok I don’t know what I did but the car started. Then died after about 45 seconds. I maybe jiggled a wire or something. Also when I took the key out my trunk opened. Now it’s no crank no start.
There are connectors between the doors and car that develop bad electrical connections, take the accordion tube and shake it and see if the car starts. I strongly advice to have the modules tested or find a shop that specializes in electrical problems.
So check this out. I removed the PCM under battery box and cleaned the connections. Plugged it back in and car started right up with problem solved. Runs great now and have not had any more issues.
Crank No Start
