CEL when ECU is grounded
05-23-2008, 11:59 AM
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CEL when ECU is grounded
I'm having a strange problem with my ECU. It's a chipped p28 with a datalogging header and toggle switches soldered inline with J1 and J12.
I tried installing a new EEPROM in my ECU yesterday; it didn't work, so I swapped the old one back in. That night, I tried to start my car, but I couldn't. I noticed the CEL was on, so I flipped the J1 switch to bypass the EEPROM. I tried again, and the car started right up. I then turned the car off, flipped the switch to J1 again, and again, it started right up.
Stupidly, I decided to drive the car, and after about 5-10 minutes, the CEL suddenly turned on, the engine died, and I pulled to the side of the road. I tried flipping the switch to J1 a few times with no luck. I then started unbolting the ECU, and I noticed that the CEL had turned off. I turned the key, and the car started up immediately. I then turned the car off and put the ECU back in place. As soon as the case touched a metal stud, I heard a click, and the CEL was back on. I noticed that whenever I touched the ECU to the stud, the CEL turned on, and whenever I isolated it, the CEL remained off.
I've tried diagnosing this today with no luck. I can't find any shorts in or around the ECU. The clicking sound I keep hearing seems to be coming from the shift interlock solenoid, but I'm not sure. I've tried pulling the code, but the CEL remains solid.
Any ideas?
EDIT: I tried a virgin p06, and there are no issues. There is some issue with the p28.
Modified by ddd4114 at 4:19 PM 5/23/2008
I tried installing a new EEPROM in my ECU yesterday; it didn't work, so I swapped the old one back in. That night, I tried to start my car, but I couldn't. I noticed the CEL was on, so I flipped the J1 switch to bypass the EEPROM. I tried again, and the car started right up. I then turned the car off, flipped the switch to J1 again, and again, it started right up.
Stupidly, I decided to drive the car, and after about 5-10 minutes, the CEL suddenly turned on, the engine died, and I pulled to the side of the road. I tried flipping the switch to J1 a few times with no luck. I then started unbolting the ECU, and I noticed that the CEL had turned off. I turned the key, and the car started up immediately. I then turned the car off and put the ECU back in place. As soon as the case touched a metal stud, I heard a click, and the CEL was back on. I noticed that whenever I touched the ECU to the stud, the CEL turned on, and whenever I isolated it, the CEL remained off.
I've tried diagnosing this today with no luck. I can't find any shorts in or around the ECU. The clicking sound I keep hearing seems to be coming from the shift interlock solenoid, but I'm not sure. I've tried pulling the code, but the CEL remains solid.
Any ideas?
EDIT: I tried a virgin p06, and there are no issues. There is some issue with the p28.
Modified by ddd4114 at 4:19 PM 5/23/2008
05-23-2008, 01:10 PM
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Re: CEL when ECU is grounded (ddd4114)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by ddd4114 »</TD></TR><TR><TD CLASS="quote">
EDIT: I tried a virgin p06, and there are no issues. There is some issue with the p28.
</TD></TR></TABLE> Sounds like you got your problem figured to me.
EDIT: I tried a virgin p06, and there are no issues. There is some issue with the p28.
</TD></TR></TABLE> Sounds like you got your problem figured to me.
05-23-2008, 01:12 PM
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Re: CEL when ECU is grounded (King V)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by King V »</TD></TR><TR><TD CLASS="quote"> Sounds like you got your problem figured to me.</TD></TR></TABLE>
I know it's something to do with the ECU, but I don't know what. I don't know what would cause this aside from a short, and I can't find any.
I know it's something to do with the ECU, but I don't know what. I don't know what would cause this aside from a short, and I can't find any.
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