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| No ses light (Page 1/2) |
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Iboughtafiero
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APR 18, 02:37 PM
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So for all you fear all mechanics out there here is a very weird thing with my 86 GT. I have no service engine light yet when I put a light tester on ground and I poke the cable A5 pen off the ECU the cable light lights up in the mill turns on This is key on engine on I remove the cable tester. The light turns off isn’t the cable tester just checking for 12 V because a five should be 12 V with Keon engine on. Basically my car does not run past the cold start ignition and I’m trying to troubleshoot. I don’t know if it’s my ECU or if it is something else now I replaced the distributor the cap, the rotor, the ICM and the big coil pack any thoughts?
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Vintage-Nut
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APR 18, 04:09 PM
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| quote | | I have no service engine light yet when I put a light tester on ground |
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Switch the ECM to Diagnostic Mode by Jumper terminal "A" to "B"
With terminal A jumpered to B, turn ignition to "ON" but do not start the engine.
Whenever the ECM is switched to Diagnostic mode, it will flash code 12 three times after which it will flash all stored trouble codes.
https://www.fiero.nl/cgi-bin/main.cgi?ECMCodes
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Original Owner of a Silver '88 GT
Under 'Production Refurbishment' @ 136k Miles
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Iboughtafiero
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APR 18, 04:26 PM
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That’s the thing I get no codes no ses. If I poke the ses wire (brn/wht) off the ecm. It lights up the Ses. I’m pretty sure the ecm is toast. Also that cable should be 12v with KOEO. It’s 6v. Battery is showing12v.
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Vintage-Nut
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APR 18, 06:01 PM
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| quote | | That’s the thing I get no codes no ses. If I poke the ses wire (brn/wht) off the ecm. It lights up the Ses. |
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I'm Confused: "no codes / no ses" BUT you say the brn/wht wire off the ecm lights up the Ses....
| quote | | Basically my car does not run past the cold start ignition and I’m trying to troubleshoot. |
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This is a step-by-step testing procedure for the ignition system and module:
How To Test The GM Distributor Mounted Ignition Module
https://easyautodiagnostics...or-mounted-icm-tests[This message has been edited by Vintage-Nut (edited 04-18-2025).]
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olejoedad
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APR 18, 07:41 PM
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The gage fuse provides power to the SES light at all times.
The ECU provides a ground path that causes the light to turn on.
Use the above chart to diagnose your problem.[This message has been edited by olejoedad (edited 04-18-2025).]
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Mike in Sydney
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APR 19, 05:27 AM
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Post omitted. [This message has been edited by Mike in Sydney (edited 04-19-2025).]
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Iboughtafiero
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APR 19, 07:01 AM
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| quote | Originally posted by olejoedad:
The gage fuse provides power to the SES light at all times.
The ECU provides a ground path that causes the light to turn on.
Use the above chart to diagnose your problem.
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I appreciate this. Though it is for 2.5 tbi. Where would I get the docs for 2.8 v6, or is the same steps?
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olejoedad
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APR 19, 08:23 AM
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olejoedad
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APR 19, 08:25 AM
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Have you checked to be sure the ECM has constant battery power?
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Iboughtafiero
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APR 19, 05:52 PM
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Yes it does. I’m getting a ecm Monday. Thanks all
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