After pulling my boat back for the lake last summer my 94 would not restart in the driveway. The engine would turn over fine, but no fire. After checking all the fuses (inside and engine compartment) I jumped the EFI relay and it fired right up. There was no electrical signal telling the relay to make, the relay bench tested fine. Upon further investigation the CEL does not come on when the key is first turned, and the alternator was not receiving the required field voltage. Nearly six months later the EFI relay jumper wire is still in place, but leaving it connected will draw down the battery over time. The plug is off the back of the alternator and I have a wire connecting the middle terminal directly to the battery so the alternator will charge. After trying to research the problem here on MUD, I replaced the fusible link behind the battery and did a quick inspection of the wiring harness on the firewall behind the EGR valve. What should I check next? Thanks in advance for your help!
1994 No power to CEL or EFI Relay or Alternator?!
- Thread starter TowRig
- Start date
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does anything inside not work? wipers, radio, etc.
Everything runs thru AM1 the 50A mega fuse in the engine bay, and thru the 2 fusible links AM1 and AM2
when you checked the fuses, did you use a test light and check for power at each fuse, or did you visually inspect the fuse?
Do you have an EWD wiring diagram book?
Everything runs thru AM1 the 50A mega fuse in the engine bay, and thru the 2 fusible links AM1 and AM2
when you checked the fuses, did you use a test light and check for power at each fuse, or did you visually inspect the fuse?
Do you have an EWD wiring diagram book?
- Thread starter
- #3
I used a test light to check most of the fuses, or an ammeter to check continuity on the larger fuses with no rear contacts.
I have both the Factory Service Manual and Electrical Manual.
Everything on the vehicle works except the check engine light, signal voltage to EFI relay, and field voltage to alternator. I jumped the EFI relay from 12V+ terminal to the output terminal, and wired the center alternator terminal directly to the battery. I might have an ignition switch problem since the CEL, signal to turn on the EFI relay, and starting voltage to alternator are all controlled by the key – but I have no idea were to look, or how to test?!?
I have both the Factory Service Manual and Electrical Manual.
Everything on the vehicle works except the check engine light, signal voltage to EFI relay, and field voltage to alternator. I jumped the EFI relay from 12V+ terminal to the output terminal, and wired the center alternator terminal directly to the battery. I might have an ignition switch problem since the CEL, signal to turn on the EFI relay, and starting voltage to alternator are all controlled by the key – but I have no idea were to look, or how to test?!?
"I might have an ignition switch problem since the CEL, signal to turn on the EFI relay, and starting voltage to alternator are all controlled by the key"
This is not correct. The CEL is illuminated by the ECU. The EFI relay logic is initiated by the ECU. The Alternator sees +12 from both the IGN fuse and CHARGE fuse.
If the AM2 fusible link was out the truck wouldn't run.
This is not correct. The CEL is illuminated by the ECU. The EFI relay logic is initiated by the ECU. The Alternator sees +12 from both the IGN fuse and CHARGE fuse.
If the AM2 fusible link was out the truck wouldn't run.
- Thread starter
- #5
I wonder if I lost power to the ECU, and by jumping the EFI Relay and the Alternator, I am back flowing current to the computer?
sounds like it. No check-light = no power to ECM.
check your ECM for power. Then trace backwards to the ignition switch.
Constant power is the red-yellow wire (pin2)
Ignition switched power is the black-blue (pin13), which runs through the IGN 7.5A fuse.
Good luck!
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