ECU resets every time car is shut off

[XpL0d3r]

Friend just bought a 98 EX, bone stock minus a radio. He can't pass inspection because the catalytic system always says not ready.

Found out power to the ECU is being lost every time the car is shut off. Replaced ECU to verify, same results.

Any ideas? Never even heard of this before... lol

 

[cgpEJ6]

Yeah that's bizarre, how does the ground on the battery look?

 

[Hecz]

CMOS battery?

 

[R3dline]

thats pretty crazy, i think thats a first for me lol

 

[RonJ]

Blown 7.5A hood Back Up fuse

 

[XpL0d3r]

Blown 7.5A hood Back Up fuse

This is what I was thinking... my friend brought the car to the guy who sold it to him since it's under warranty. He's getting it fixed for free regardless; I just thought it was a really strange issue.

We'll see.. once I find out what the issue was for sure I'll update...

 

[got traction]

how does that affect anything? ECUs get swapped all the time and no issues.

 

[RonJ]

how does that affect anything? ECUs get swapped all the time and no issues.

Not sure what your question is here.

 

[got traction]

"power is lost to ecu everytime car is shut off" -- well isnt power lost to ecu when it is unplugged from harness? ECU's are swapped all the time and there is no issues like OP stated.

If this still does not make sense then im sorry. Pretty hammered right now

 

[TigBitties]

i think the problem is for inspection. Atleast in PA, if you swap a ecu or clear a check engine light, you have to drive so many miles for something to set up, idk what it is, but its involved with the emissions insepctions.

example would be if your running a obd2 car off an obd1 ecu, you would have to swap it and drive about 50 or so miles or you will fail

 

[RonJ]

Correct. The Back Up fuse powers the circuit that allows the ECU to store learned information. If this circuit does not get power, then the ECU cannot store learned information and will indicate a "not ready" status for emissions testing.

 

[Blood_Shot]

f**k PA emissions

 

[XpL0d3r]

Correct. The Back Up fuse powers the circuit that allows the ECU to store learned information. If this circuit does not get power, then the ECU cannot store learned information and will indicate a "not ready" status for emissions testing.

Yep. He replaced the fuse though, still no dice


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[RonJ]

Yep. He replaced the fuse though, still no dice

Click the Fuses link in my signature. Do both top test tabs of the Back Up fuse have battery voltage to body ground? If so, next test whether ECU terminal C10 has battery voltage to body ground.

 

[XpL0d3r]

found out it was a bad wire somewhere causing the issue... not sure which one though.

it's all fixed now, thanks fo the help

 

[MugenRR]

maybe the ecu fuse is missing.
cheers

 

[obracer12]

^ then it wouldn't start at all...

This is an odd one.. The back-up fuse was a thought, but if that's not it, I would have to say to check the wires at connector A pins 4&5, 23&24 OR Connector E pins 3&4, and trace them back for breaks/metal contact... other then that I'm at a loss...

 

[XpL0d3r]

found out it was a bad wire somewhere causing the issue... not sure which one though.

it's all fixed now, thanks fo the help

 

[obracer12]

^ woops... too late and reading>me

 

[IlDuce]

Ok i have a question. I see that there is an issue pointing to Blown 7.5 fuse.. Will having a blown fuse hinder performance? the numb nut who wired the radio in the car wired the main power to the back up line.. ex: Radio resets every time i turn the car off.. If i put in the back up fuse (7.5) the radio doesnt shut off. my ECU was chipped, i dont know with what.. need to check on that.

Is it causing performance issues by not having the backup fuse in?