Crazy Electrical issue 1986 22RE

GeoRoss

 
Joined
Dec 4, 2004
Messages
1,961
Location
Tucson AZ
I developed a cold no-start last week when I tried to drive home after work. I went to start and acted like a dead battery, no gauge, fan, clock, radio and buzzer. However, the dome light was dim and the rear window worked normally with the key. I'm at work and all I had was my free HF DMM (which failed LOL) and a mini leatherman tool. The symptoms led me to believe it was a fuse. I pulled and visually checked the big 30A and 40A AM fuses, visually inspected the 80A and they looked fine. I checked the usual suspects on the bladed fuses and they looked fine. I'm at work and stumped. I noticed though after pulling and checking fuses the dome light was back to full brightness. I put the key in and everything came back, radio, gauges, fan, buzzer, clock. I turn the key and it starts. Woo-Hoo! I can get the 4Runner home.

That night I recreated the problem. I turn the key to run and everything works. I go to start it and everything dies. I wiggle the AM fuses and things come back. I try to start and everything goes dead. Well this officially became a weekend project.

I check voltages at the AM fuses and they look fine. I pull the 80A and it seems fine. I check resistance and they seem fine. I inspected all the connections in the relay box and they looked solid. No wiggling, no wire damage and no corrosion. Since it looks like circuits for both AM fuses I start looking at the 80A. I clean all the contacts put it back together. I go the the F1 connector by the airbox and clean those contacts. Nothing really looked corroded. Nothing really looked out of place except I did find an abandoned trailer light box behind the airbag that was scotch locked to the tail lights in the cab. :eek: I pulled and fixed that. It couldn't have been involved, but what the hey.

Everything works now and has since last Saturday. First, I am a complete loss at the symptoms. The AM fuses were almost acting like breakers. I have no clue how to explain those symptoms.

Anyone smarter than me have any ideas? That should include everyone. I didn't do any load testing which I guess would be the next step. While I'm glad the 4Runner is working, I'm not a fan of self-healing electrical problems.
 

fj55-100

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Joined
Jun 16, 2003
Messages
906
small load . like lights radio gauges that works but then goes away as more demand is required is a .. load problem ... like a bad batery terminal .. or a corroded cable in the insluation hidden from sight .. or a ground from the battery to the engine block and back to the body ... or in rare times a battery post lose in the case .... yours sounds ground related ..start at the terminals clean and inspect it back to the block ..
 

GeoRoss

 
Joined
Dec 4, 2004
Messages
1,961
Location
Tucson AZ
The hidden corrosion or possibly an iffy ignitor switch
small load . like lights radio gauges that works but then goes away as more demand is required is a .. load problem ... like a bad batery terminal .. or a corroded cable in the insluation hidden from sight .. or a ground from the battery to the engine block and back to the body ... or in rare times a battery post lose in the case .... yours sounds ground related ..start at the terminals clean and inspect it back to the block ..
These are good ideas. All grounds and battery connections were checked and cleaned up awhile ago. I have not taken the loom apart anywhere yet. There is no corrosion at any wire ends, nice clean copper. I will take the looms apart and inspect everything between the relay box and the battery. That must be where the problem is.

What is really creepy is how it acts like a breaker. It is definitely load related, but why did wiggling the AM fuses bring back the low load stuff?
 
Joined
Jun 25, 2012
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Delburne, Alberta
Careful not to overthink this. I agree with fj55-100. I once had a similar condition caused by worn battery posts under terminals that looked great but were maxed out for tension and eventually wiggled themselves floppy. Start simple. Just because your connections were good then doesn't mean something hasn't changed. Best of luck.
 

pappy

photosynthesizing
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Oct 7, 2003
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9,419
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Too far north. Too far east.
Once one of my grounds was broken inside the terminal connector. Looked clean and new until I accidentally pulled on it.
Careful not to overthink this. Start simple. Just because your connections were good then doesn't mean something hasn't changed. Best of luck.
It's always something simple. Good job.
 
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