LT1 Based Engine Tech 1993-1997 LT1/LT4 Engine Related

Ignition no power problem

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Old Dec 8, 2023 | 11:49 AM
  #1  
Husker973's Avatar
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Ignition no power problem

I have a 1996 camaro z28 i just bought.I noticed that the cooling fan is running all the time when car is on. I checked the fuse box and noticed a jumper wire from the number 3 cooling fan relay to the ignition fuse. I took the jumper wire off and noticed the car wouldn’t start, just crank. The ignition fuse gets no power without it jumped from the cooling fan. Wondering what might have caused this.



Old Dec 8, 2023 | 04:29 PM
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Re: Ignition no power problem

Possibly the 12 volt supply wire to the ignition fuse is not functional, so they tapped fan #3 relay to provide 12 volts. Just a guess.

Ignition fuse should be 10 amp, supplying the ignition coil module (ICM) and the ignition coil. Also supplies the crankshaft position sensor, but that is only used for misfire detection, and will not prevent the engine from starting.

Have you scanned for codes? Is the SES light functional in "bulb check"?

Beyond that, all I can do is offer you a free download of the 1996 factory service manual, courtesy of GaryDoug:

https://www.mediafire.com/?40mfgeoe4ctti

Old Dec 8, 2023 | 04:59 PM
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Re: Ignition no power problem

It has codes p1641, P0400,p0412 and p1642
Old Dec 8, 2023 | 07:13 PM
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Re: Ignition no power problem

P1641 and P1642 set because the fan relays were “on” when they were supposed to be off.

P0400 is for the EGR system…. not related to the jumper wire. P0412 is for the secondary AIR system control. Those last two appear to be related to the previous owner disabling emissions.

Was the “SES” light on? Should be with those codes. Does the “SES” light come on during the 3-second bulb check when you turn the key to “RUN”. If not, someone may have disabled the bulb to cover up a lot of problems with the car.
Old Dec 13, 2023 | 10:44 PM
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Re: Ignition no power problem

Yep, someone "white-guy rigged" it up badly. You car has a wiring problem and the fix was a band-aid. We may be able to get to the bottom of this if you are willing to do a lot of work. I am available next year about mid-January ;-)

Last edited by GaryDoug; Dec 13, 2023 at 10:48 PM.
Old Jan 7, 2024 | 11:18 AM
  #6  
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Re: Ignition no power problem

Wonder if he figured this out. Came back to this site on 1/2/24, but didn't bother to update us.
Old Jan 7, 2024 | 10:06 PM
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Re: Ignition no power problem

Originally Posted by Injuneer
Wonder if he figured this out. Came back to this site on 1/2/24, but didn't bother to update us.
The connection was very loose where the ignition fuse goes in. Just had to tighten it.
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