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MAJOR electrical problems after fuel pump replaced

wayc4

Full Member
Joined
Nov 20, 2021
Messages
12
First of all, thanks for the add to the group.
I have a 2002 Avy, 1500 series. Last wee my fuel pump went out and had it replaced. Before replacing the pump, everything on this truck worked perfectly, no electrial issues of any kind. The truck was towed to the shop, rear wheels up bu a wrecker service. When picked it up at the shop after fuel pump installed, i noticed the BATT service light stayed on after cranking the truck, i also noticed, the odometer and gear selection lighting was not working. I asked the mechanic about it, said he had no idea, stating " we replaced the fuel pump, dont know if was like that when you brough it in OR NOT."
The truck cranks and run fine, BUT;
odometer and gear selection readout not working, windshield wiper/washer not working, HVAC controls not working, HVAC fan not working, BATT light stays on (alternator/batterylight check out fine), TRACTION OFF light stays on, TOW/HAUL light will not come on, Bright Head indicator will not come on, if you switch between bright and dim headlight, only either one will work , either the outer or inner lights work, not both, all the guages work except the temperature guage, all the instrument cluster lights work. All of the fuses are good, all the relays are good, both under the hood and in the cab area. The odometer and gear selection read out work wit the key in the on position but go off when the engine cranks and is running, NEED HELP PLEASE, THANKS
 
Check ground wires for the bunch of them... all over and under truck.
 
Check ground wires for the bunch of them... all over and under truck.
thanks, have checked everything except that, the mechanic was very quick to state they never touched anything electrical,"didnt even disconnect the battery, just unplugged the pump wires", kinda risky i thought, since i had justed filled the tank the day before the pump died with close to 30 gallons of gas.
 
Thanks for the add, sorry my firt posst is a plea for help, but what better place , right?
have a 02 avy that developed major eelctrical issues whe i had the in-tank , electric fuel pump changed. Before fuel pump installed no issues at all, none. When i picked up the truck at the shop, before leaving the shop, I notice my battery light remained on after starting it. Questioned the mechanic, was told they noticed that also , but didnt know if was on before their repairs or not, and they had checked the battery and alternator and both were fine. Also noticed, the heater and a/c controls and fan did not work and their back lighting did not work. The odometer and gear shift lighting worked on in the ignition ON position but went dark when the engine was running, the windshield wipers/washer didnt work, the Traction Off light stay on, the TOW/HAUL switch didnt work, with the head lights on, if you turn on the dims they work, if you turn on the high beam, the low beams go off and the high beams come on but not the dash indicator light. The avy cranks and runs fine. Have checked all the fuses and relays, have actually traded them out with new ones sequentially, nothing helped, Have checked all the ground wires, all tight and good contact. Really need some help, thanks
 
Thats a lot of crap to stop working all at once.

I'd probably pull the fuel pump relay and any fuses associated with it. And then check everything else. If there was something screwy with the new pump, that should take it out. A short is just about the only reason for lights to be dimmer when the truck is running. One of the few things that is on only when running is the fuel pump circuit.

Unfortunately I think most of the other issues stem from devices that routes though the body control module.

Id probably pay to have the dealer diagnose the issue just to prevent he said she said. I'm not certain whether this is coincidence or not. They would have the scanners to plug in and give the modules a check to find the root cause.

If it is a control module issue, then that's probably going to be a pain in the ass to find a proper part for. (Model year compatibility) . It would then be an issue of what caused it to fail. Did someone short out the battery on accident when doing the repair? Was it just it's time to go? Something stupid like a random broken wore by coincidence?
 
Thats a lot of crap to stop working all at once.

I'd probably pull the fuel pump relay and any fuses associated with it. And then check everything else. If there was something screwy with the new pump, that should take it out. A short is just about the only reason for lights to be dimmer when the truck is running. One of the few things that is on only when running is the fuel pump circuit.

Unfortunately I think most of the other issues stem from devices that routes though the body control module.

Id probably pay to have the dealer diagnose the issue just to prevent he said she said. I'm not certain whether this is coincidence or not. They would have the scanners to plug in and give the modules a check to find the root cause.

If it is a control module issue, then that's probably going to be a pain in the ass to find a proper part for. (Model year compatibility) . It would then be an issue of what caused it to fail. Did someone short out the battery on accident when doing the repair? Was it just it's time to go? Something stupid like a random broken wore by coincidence?
Thanks for your response. To clarify, the headlights dont not dim with the truck running, only the lower beams work or ony the high beams work, depending on which one is on, in other words if i have the lower beams on they work, if i switch on the high beams, the lower beam go off and the high beamss come on, but the high beam dash indicator light does not illuminate. All other exterior lighting works proerly. All the guages work. All interior lighting works except the A/C and heater switch back lighting and fan doesnt work. Strange for sure,again thanks
 
You stated that the fan doesn't work.
Well why not start with that?
Check the fuse, check to see that the fan motor is receiving power AND ground.
IF the ground portion of the circuit is missing - then there is strong evidence that a ground wire is missing/disconnected/broken somewhere.
Back when I was still a mechanic, a car came in with a platoon of DTCs. After checking the basics, I discovered that some yokel had changed the battery, and broke the main body ground...and had either forgotten to or couldn't be bothered repairing it. Well - guess what?
All the weird DTCs and other strange operational issues disappeared after I repaired that body ground.
So there you have it. Start with the basics, to see if anything stupid has been missed - and go from there.
 
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