Computer code 543

[callys]

I have a 1994 5.0 and my 02 sensors were bad so i replaced them then i scanned the computer to see if the bank 1 and 2 lean codes were gone, and they were. However, while running the engine on test i got engine code 543 which basically says there is an open connection between the fuel pump and the battery. Thing that is really pissing me off is I didnt touch anything else. I jacked up the car, replaced the sensors, put the car down, ran the test. Does part of the fuel pump relay run through the O2s? I checked all the fuses in the engine compartment fuel box and they all came out fine. The even weirder thing is the car started at first and ran then gave me the code and then it wouldnt start.

Any suggestions at all? Otherwise I guess I have to get it towed to an electrical shop.

edit - I read the 543 diagnostics write up, I will try putting in one of the old o2 sensors on the left side.

 

[wytstang]

You didn't say if you cleared all the codes or not. Clear all of they if you haven't do so already.

 

[HISSIN50]

So after doing lambdas, the car wont start? You're smart to look for a short. IIRC, if the lambda shorts out, it triggers a secondary fuel code. Look for bad wiring and pins while checking things out. The connectors can get corroded or just oily.

Good luck.

 

[callys]

I tried replacing the left O2 sensor and I checked out the pins on both male and female connectors several times... I dont see anything wrong. I guess I will have to try to trace the wires all the way up.

Wystang how would I go about clearing the codes? I don't have an aftermarket tuner, I just have an EEC reader. Do you mean just reseting the computer?

Right now the fuel pump will not come on at all. I turn the key forward and get nothing (no hum)

I guess I will end up taking the wrapping off the trail of wires that snakes up the front of the engine and looking for something torn or shorting

 

[wytstang]

Yeah just resetting the computer, disconnect the batt for about 10min that will clear the codes.

 

[HISSIN50]

What happened if you disconnected both O2 wiring harness connections? It is possible to get a bad or wrong O2 and have it cause an issue.

IIRC there's a fuel pump fuse - I would check it real quick and make sure it didnt blow due to the ancillary issue.

Good luck.

 

[mo_dingo]

does the fuel pump cycle when you turn the key to acc???