Steve@Advance
Well-known Member
About 2 weeks ago I posted about an 08 F350, 6.4, having strange electrical issues. The instruments would go to zero, AC blower cut off, radio go off, all happening at random times.
This all started after I replaced the alternator.
I went back, retraced everything I did, made sure everything was right, nothing loose, no pinched wires. Checked for voltage differentials between the frame, chassis, engine. Found nothing of any consequence. Just to say I did it, I took several ground wires loose, sanded the paint away, and reconnected. I took the left fender well out, unplugged, inspected, reconnected the 3 harness plugs.
I checked the voltage output, around 14.7.
Drove the truck for about an hour, drove through rough back roads trying to jar something loose. Could not replicate the problem, so assumed maybe I corrected it by cleaning the grounds and reseating the harness connectors.
Gave it back to the owner, he drove it for 2 days, it started doing it again. We agreed it would be a waste of time for me to dive back in blind, so he took it to a diesel specialty shop he had used before.
They have the specialty equipment and software to monitor the electrical systems, just like the dealer has.
They checked the same things I did, then drove it around for 3 days before anything happened! That's 3 days @ $100 an hour! Finally it acted up. The computer said the voltage was up to 20 volts!
JSTPA, you got it right, high voltage was shutting down the computer(s)! Just a matter of catching it in the act.
The diesel shop let me exchange the alternator under warranty. I bought it at a starter/generator/alternator shop. Had a long conversation with the owner, he said it is possible the alternator was defective, but it could also be in the ECM, as it also controls the voltage.
It's been 5 days now, all is well. Lets hope this episode is over!
Thanks everyone!
This all started after I replaced the alternator.
I went back, retraced everything I did, made sure everything was right, nothing loose, no pinched wires. Checked for voltage differentials between the frame, chassis, engine. Found nothing of any consequence. Just to say I did it, I took several ground wires loose, sanded the paint away, and reconnected. I took the left fender well out, unplugged, inspected, reconnected the 3 harness plugs.
I checked the voltage output, around 14.7.
Drove the truck for about an hour, drove through rough back roads trying to jar something loose. Could not replicate the problem, so assumed maybe I corrected it by cleaning the grounds and reseating the harness connectors.
Gave it back to the owner, he drove it for 2 days, it started doing it again. We agreed it would be a waste of time for me to dive back in blind, so he took it to a diesel specialty shop he had used before.
They have the specialty equipment and software to monitor the electrical systems, just like the dealer has.
They checked the same things I did, then drove it around for 3 days before anything happened! That's 3 days @ $100 an hour! Finally it acted up. The computer said the voltage was up to 20 volts!
JSTPA, you got it right, high voltage was shutting down the computer(s)! Just a matter of catching it in the act.
The diesel shop let me exchange the alternator under warranty. I bought it at a starter/generator/alternator shop. Had a long conversation with the owner, he said it is possible the alternator was defective, but it could also be in the ECM, as it also controls the voltage.
It's been 5 days now, all is well. Lets hope this episode is over!
Thanks everyone!
