EEC-IV codes 542, 543

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06-15-2006, 11:07 PM

yellow95 347

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Join Date: Mar 2005

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EEC-IV codes 542, 543

Anyone ever run into these codes before? I've got the definitions, just not sure exactly where to look for the problems.

It's a 95 gt - 5 speed.

I'm pulling the 542 from the KOEO test. I get both from the memory codes.

542 O,C Fuel pump circuit open; ECA to motor
543 O,C Fuel pump circuit open; battery to ECA

06-16-2006, 01:15 AM

sc94gt

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RE: EEC-IV codes 542, 543

Sounds like a bad ground somewhere... maybe the EEC to the motor.

06-18-2006, 11:39 PM

yellow95 347

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RE: EEC-IV codes 542, 543

Yeah, that's kinda what I was figuring, just didn't know where to look for the ground (on the motor). I just did some checking......from the computer (pins 40 and 60) to engine ground as well as body ground......seem fine. I have a couple more grounds that I'm going to check tomorrow, but after that I'm thinking maybe bad ECM???

Both O2 sensors are reading lean as well, but the exhaust is definately rich....

06-19-2006, 12:40 AM

Joel5.0

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Join Date: Jan 2006

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Posts: 3,926

RE: EEC-IV codes 542, 543

Quote:

ORIGINAL: yellow95 347

Yeah, that's kinda what I was figuring, just didn't know where to look for the ground (on the motor). I just did some checking......from the computer (pins 40 and 60) to engine ground as well as body ground......seem fine. I have a couple more grounds that I'm going to check tomorrow, but after that I'm thinking maybe bad ECM???

Both O2 sensors are reading lean as well, but the exhaust is definately rich....

You could have a short between Ign power and O2's signal (bad O2's or wiring), a bad CCRM module, wiring problem or a bad ECM....does the engine start?