problem with PCM
07-22-2013, 07:54 AM
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problem with PCM Hi,
I have a 1999 4.8 with a 4L60E RWD and the computer coming from the 4.8.
These all are installed into a GM D-body. I also have an electric fan.
The car runs, for the past three weeks I have been using it every day the weather is nice.
The problem is I cannot communicate with the PCM when I try to plug an OBDII scanner. I have tried it with two scanners. I have the OBDII plug out of a 1999 truck so the pins are at the same locations. I checked that I have two grounds on pins 4 and 5, battery + on pin 16 and data signal on pin 2. I get an error when I plug the scanner.
How can I know I get a signal on pin 2 from the PCM?
What is the voltage I should get?
How can I make sure the PCM works properly?
Can the car run fine but the circuit for the OBDII communication be damaged?
I read that one sign the PCM gets damaged is when the fan starts with the key on. I remember once the fan kicking in when I just started the engine and I found that weird. But it only did it once and everything seems to run fine.
Any tips?
Thanks
I have a 1999 4.8 with a 4L60E RWD and the computer coming from the 4.8.
These all are installed into a GM D-body. I also have an electric fan.
The car runs, for the past three weeks I have been using it every day the weather is nice.
The problem is I cannot communicate with the PCM when I try to plug an OBDII scanner. I have tried it with two scanners. I have the OBDII plug out of a 1999 truck so the pins are at the same locations. I checked that I have two grounds on pins 4 and 5, battery + on pin 16 and data signal on pin 2. I get an error when I plug the scanner.
How can I know I get a signal on pin 2 from the PCM?
What is the voltage I should get?
How can I make sure the PCM works properly?
Can the car run fine but the circuit for the OBDII communication be damaged?
I read that one sign the PCM gets damaged is when the fan starts with the key on. I remember once the fan kicking in when I just started the engine and I found that weird. But it only did it once and everything seems to run fine.
Any tips?
Thanks
07-22-2013, 12:15 PM
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I did check everything. The grounds are good. I connected them to a wire that goes to the alternator bolt. I also get voltage between pin 16 and both grounds.
I also checked all these at my OBDII plug AND through the scanner cable to make sure the cable is not damaged or doesn't make good contact.
I also verified twice that my pin 2 (data) cable has contact to the PCM connector (pin 58 on blue connector for these years)
So could it be that the car runs fine but that particular circuit is burnt in the PCM?
Can something be fixed through the software?
How do I verify that pin 2 (data) works properly? Can I measure voltage?
I also checked all these at my OBDII plug AND through the scanner cable to make sure the cable is not damaged or doesn't make good contact.
I also verified twice that my pin 2 (data) cable has contact to the PCM connector (pin 58 on blue connector for these years)
So could it be that the car runs fine but that particular circuit is burnt in the PCM?
Can something be fixed through the software?
How do I verify that pin 2 (data) works properly? Can I measure voltage?