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87 SES light on

Old 10-11-2018, 04:53 AM
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ron4811
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Default 87 SES light on

My 87 has SES light on and I can't read codes, the B connector in ALDL does not have power and there is no power at 3 amp ecm fuse in or out. Engine runs but fast idles and last week i started to pull out at quarter throttle and backed off and engine shut down immediatly. Does anyone have an idea what problem might be?
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Old 10-11-2018, 10:44 AM
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aklim
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What did you back out? The throttle adjustment screw? I don't think you can adjust idle speed at all like that. I would put it back to where it was and see what it does.
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Old 10-11-2018, 12:32 PM
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Default Try pulling codes



Originally Posted by ron4811 View Post
My 87 has SES light on and I can't read codes, the B connector in ALDL does not have power and there is no power at 3 amp ecm fuse in or out. Engine runs but fast idles and last week i started to pull out at quarter throttle and backed off and engine shut down immediatly. Does anyone have an idea what problem might be?
RON4811;
If it's running the ECM must be getting power from somewhere. With the engine off, turn the ignition to on and try shorting the A-B on the ALDL and see if you get codes of any kind. You should see the SES flash 12, 12, 12 - (your code(s) ) - 12, 12, 12. Do not start the car with A-B shorted!
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Old 10-11-2018, 12:45 PM
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Originally Posted by rharker View Post



RON4811;
If it's running the ECM must be getting power from somewhere. With the engine off, turn the ignition to on and try shorting the A-B on the ALDL and see if you get codes of any kind. You should see the SES flash 12, 12, 12 - (your code(s) ) - 12, 12, 12. Do not start the car with A-B shorted!
Would that work if he was getting no power at the fuse? I think he should get it running again and then sort things out.
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Old 10-11-2018, 12:53 PM
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Originally Posted by aklim View Post
Would that work if he was getting no power at the fuse? I think he should get it running again and then sort things out.

It may not but it would be another symptom. If it runs at all then power is going to the ECM injector drivers ... But it seems to me it's time to check the troubleshooting charts in the FSM ... each code set has its own chart.
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Old 10-11-2018, 01:16 PM
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I think you should re-read his post. He didn't say he backed anything out. He let off the throttle and the car died. At least that is the way I understood it.
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Old 10-11-2018, 01:52 PM
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Originally Posted by cdm747 View Post
I think you should re-read his post. He didn't say he backed anything out. He let off the throttle and the car died. At least that is the way I understood it.
My bad. I thought he backed something out.
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Old 10-11-2018, 03:16 PM
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I think the 1st order of business it to get power to the ALDL so it can be used as the diagnostic tool intended.
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Old 10-11-2018, 06:08 PM
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Thanks for the replies, I did not back out adjustments, was went from quarter throttle to closed throttle and engine quit. The car will start fine every time but has a fast idle when it should not, even when at operating temp. When I short A and B with key on engine off I get no codes, not even the 12. SES is on the whole time engine is running. B has no power and 3 amp fuse has no power. I am loosing power before it gets to ecm, the main power from battery to ecm is good which is what allows engine to run. I need to know how to get power back to 3 amp fuse and ALDL B
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Old 10-12-2018, 12:25 PM
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Default this is from an 86 but should help

Originally Posted by ron4811 View Post
Thanks for the replies, I did not back out adjustments, was went from quarter throttle to closed throttle and engine quit. The car will start fine every time but has a fast idle when it should not, even when at operating temp. When I short A and B with key on engine off I get no codes, not even the 12. SES is on the whole time engine is running. B has no power and 3 amp fuse has no power. I am loosing power before it gets to ecm, the main power from battery to ecm is good which is what allows engine to run. I need to know how to get power back to 3 amp fuse and ALDL B






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Old 10-12-2018, 05:58 PM
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Thank you rharker, these charts are great, I think they will lead me to the problem. Just at a quick glance without checking I think the ecm is bad. I may not get to check it til next weekend but will let you know what I find. Thanks again. Ron
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Old 10-12-2018, 08:28 PM
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Are your fans running along with the high idle? I think thats another symptom of a bad ecm.
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