Check engine light stay on with key off
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Junior Member
Joined: Jul 2007
Posts: 42
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From: Houston
Car: 86 Iroc Z
Engine: Built 305
Transmission: 700R4
Axle/Gears: 3.73
Check engine light stay on with key off
FIXED!!
Well my car has been running great lately. Drove it around all day today. But when I got home tonight and turned it off the check engine light came on. Its only comes on when I turn the key off. Its not on while the car is running and the car still runs fine. Also the fan was staying on. But the car isn't overheating. Its like they key is still in the one position. But when I turn the key to the on position the check engine light goes off. Any suggestions?
Well my car has been running great lately. Drove it around all day today. But when I got home tonight and turned it off the check engine light came on. Its only comes on when I turn the key off. Its not on while the car is running and the car still runs fine. Also the fan was staying on. But the car isn't overheating. Its like they key is still in the one position. But when I turn the key to the on position the check engine light goes off. Any suggestions?
Last edited by 86Z28beast; Sep 30, 2010 at 07:20 PM.
Supreme Member
Joined: Jan 2006
Posts: 3,341
Likes: 10
From: Mooresville NC
Car: LOWERED ♦ CRIMSON METALFLAKE
Engine: ► 400 KUBES ◄
Transmission: 765R4
Axle/Gears: EATON POSI 4.56
SES Mess
With the key in the OFF position, remove the GAGES fuse.
Does the SES light go out?
Then reinsert the GAGES fuse.
Now, with the key still in the OFF position, remove the ECM fuse.
Does the SES light go out?
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I Didn’t Wreck, The Track Moved
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Does the SES light go out?
Then reinsert the GAGES fuse.
Now, with the key still in the OFF position, remove the ECM fuse.
Does the SES light go out?
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Happy Racing!
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I Didn’t Wreck, The Track Moved
.
Thread Starter
Junior Member
Joined: Jul 2007
Posts: 42
Likes: 0
From: Houston
Car: 86 Iroc Z
Engine: Built 305
Transmission: 700R4
Axle/Gears: 3.73
Re: Check engine light stay on with key off
Battery was dead when I came out this morning. So I put in another battery I had laying around. As soon as I put in and rehooked up the fan. The fan came on. So I went and pulled the fan fuse. It shut off. But the check engine light stays on. With all the fuses pulled under the dash the check engine light stays on. Where else would the fuses be for the ecu? Or is there a relay that might be stuck on that goes to the ecu?
Thread Starter
Junior Member
Joined: Jul 2007
Posts: 42
Likes: 0
From: Houston
Car: 86 Iroc Z
Engine: Built 305
Transmission: 700R4
Axle/Gears: 3.73
Re: Check engine light stay on with key off
No its a factory TPI car. I'm still using the factory setup. I'm just disconnecting the ground cable now so the battery won't drain. Been driving the car around today and it still runs fine. Havn't figured it out.
Last edited by 86Z28beast; Sep 27, 2010 at 06:48 PM.
Joined: Aug 1999
Posts: 5,261
Likes: 461
From: RI
Car: 1984 Camaro Berlinetta
Engine: LT1
Transmission: T56 6-speed
Axle/Gears: 4.11 LS1 Rear End
Re: Check engine light stay on with key off
Carb cars have a "lamp driver" between the ECM and the C/E warning light, but FI cars do not. It's gotta' be the ECM, Wiring, or the cluster.......
Try NINA's suggestions to quickly find out what circuit is supplying the C/E bulb with power......
Try NINA's suggestions to quickly find out what circuit is supplying the C/E bulb with power......
Thread Starter
Junior Member
Joined: Jul 2007
Posts: 42
Likes: 0
From: Houston
Car: 86 Iroc Z
Engine: Built 305
Transmission: 700R4
Axle/Gears: 3.73
Re: Check engine light stay on with key off
I did try that. Pulled all the fuses. The check engine light still stays on. Is there another fuse location other then the one under the driver dash panel?
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Supreme Member
Joined: Jan 2006
Posts: 3,341
Likes: 10
From: Mooresville NC
Car: LOWERED ♦ CRIMSON METALFLAKE
Engine: ► 400 KUBES ◄
Transmission: 765R4
Axle/Gears: EATON POSI 4.56
SES Mess
OK with the key OFF, GAGES and ECM fuses removed, remove the under-hood fuse near the battery.
Does the SES light go out?
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Happy Racing!
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How bout those too scared to drive without headlights in the daytime
and the ones that need headlights for a little rain
.
Does the SES light go out?
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Happy Racing!
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How bout those too scared to drive without headlights in the daytime
and the ones that need headlights for a little rain.
Thread Starter
Junior Member
Joined: Jul 2007
Posts: 42
Likes: 0
From: Houston
Car: 86 Iroc Z
Engine: Built 305
Transmission: 700R4
Axle/Gears: 3.73
Re: Check engine light stay on with key off
Pulled all the fuses and the one by the battery. The check engine light still stays on. Something is staying on. Is there a relay for the ecu or something? With all the fuses out when I reconect the ground it still sparks pretty good. Where are the relays located other then the ones on the driver side by the brake booster?
Supreme Member
Joined: Jan 2006
Posts: 3,341
Likes: 10
From: Mooresville NC
Car: LOWERED ♦ CRIMSON METALFLAKE
Engine: ► 400 KUBES ◄
Transmission: 765R4
Axle/Gears: EATON POSI 4.56
SES Mess
There is no relay for powering the ECM.
Because the SES light still comes on, you missed a fuse or the PO rewired something.
Unplug the ECM.
Does the SES light still illuminate with key in the OFF position?
If it does: With the fuses removed and ECM still unplugged, find out if the pink/black wire in the dash connector has power.
(Wire colors are subject to change year to year.)
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Happy Racing!
◙◙◙◙◙◙◙◙◙◙◙◙◙◙◙
I’ve NEVER Hit The Wall! - The Safer Barrier Prevented It
.
Because the SES light still comes on, you missed a fuse or the PO rewired something.
Unplug the ECM.
Does the SES light still illuminate with key in the OFF position?
If it does: With the fuses removed and ECM still unplugged, find out if the pink/black wire in the dash connector has power.
(Wire colors are subject to change year to year.)
◙◙◙◙◙◙◙◙◙◙◙◙◙◙◙
Happy Racing!
◙◙◙◙◙◙◙◙◙◙◙◙◙◙◙
I’ve NEVER Hit The Wall! - The Safer Barrier Prevented It
.
Thread Starter
Junior Member
Joined: Jul 2007
Posts: 42
Likes: 0
From: Houston
Car: 86 Iroc Z
Engine: Built 305
Transmission: 700R4
Axle/Gears: 3.73
Re: Check engine light stay on with key off
Thanks for the help.Well the car is fixed. The alternator went out on me today. I replaced the alternator and all my issues went away. My guess would be that power was backfeeding from the terminal on the alternator keeping the ecu powered up. Thanks again for the help.
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