95 Wrangler 4.0 Just shut off - no start - Page 2 - JeepForum.com
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post #16 of 33 Old 08-24-2021, 04:06 PM Thread Starter
RH31379
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I tested pins 3,4,5,9,11 and 12. All tested correct except pin 4. Circuit k4 sensor ground. So I'm assuming if there is a problem in that circuit I'm not getting the signal to the ASD to send voltage to the coil.

Any thoughts or direction to go? Trace each sensor back to ground?

am I thinking about this wrong? I checked these with the ECM unplugged. Does the ECM send ground to these circuits? Should I check with it plugged in?

Thanks


besides the 83 cj-7, also have an 87 yj, 6cyl., 5spd, weber upgrade, 6.5' western uni mount plow, also a 2000 Sahara, 4.0, 5 spd
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post #17 of 33 Old 08-27-2021, 06:16 PM Thread Starter
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Any ideas? Gonna get back at it in the morning. Thanks

besides the 83 cj-7, also have an 87 yj, 6cyl., 5spd, weber upgrade, 6.5' western uni mount plow, also a 2000 Sahara, 4.0, 5 spd
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post #18 of 33 Old 08-28-2021, 02:54 PM
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Yes check with it plugged in

[size=3]Shackles & D-rings are different things.
Cranking IS turning over
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post #19 of 33 Old 08-29-2021, 06:12 PM Thread Starter
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Looks like the pcm is not sending ground to the ASD relay. All the power and grounds check out so I think it's time for to get the pcm rebuilt

besides the 83 cj-7, also have an 87 yj, 6cyl., 5spd, weber upgrade, 6.5' western uni mount plow, also a 2000 Sahara, 4.0, 5 spd
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post #20 of 33 Old 08-30-2021, 05:14 AM
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Check the pcm main ‘ground’ where it sources neg(-) first. A wildcard, but it can’t properly close the circuit if it is using “all” of the continuity of the connection
(You may have already eliminated that; dunno)

[size=3]Shackles & D-rings are different things.
Cranking IS turning over
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post #21 of 33 Old 09-22-2021, 06:29 PM Thread Starter
RH31379
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Just got my ECM rebuilt and it didn't do the trick. Still no start. I get the check engine light when I turn the key on. I didn't get a chance to check the ground to the ASD relay yet but I'm looking for ideas and suggestions on what else may be causing this.
Someone suggested a ground 02 sensor? Could it be the ignition switch? Any suggestions are appreciated.

besides the 83 cj-7, also have an 87 yj, 6cyl., 5spd, weber upgrade, 6.5' western uni mount plow, also a 2000 Sahara, 4.0, 5 spd
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post #22 of 33 Old 09-22-2021, 07:03 PM
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A few quick things. It your check engine light comes on your ECM has at least basic power and ground. It really sounds to me like your control 85 /86 side of your ASD relay is the issue. Find the power side and make up a headlight bulb test light and test from that wire to ground. Then, test the ground side with one side hooked to the battery and then the ground side of the relay. Key on it should light for a second or two and then shut off until the engine cranks. It it does not light key on for a second or two you have high resistance in the circuit or a bad ECM. If it lights for a second or two and the does not light when you crank the engine you probably ( like 99.9%)have a bad crank sensor or wiring to the crank sensor.

If you cannot fix it with a hammer then it has to be an electrical problem.
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post #23 of 33 Old 09-22-2021, 08:11 PM Thread Starter
RH31379
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I didn't check since I put the rebuilt ECM in tonight but prior to I was not getting ground to the ASD relay from the ECM. It seemed like all ground to the ECM were good but not ground signal out to trip the relay. I changed the CPS 1st when it 1st died. Assuming the ECM is fully functional since it was rebuilt what could cause high resistance in the circuit?

besides the 83 cj-7, also have an 87 yj, 6cyl., 5spd, weber upgrade, 6.5' western uni mount plow, also a 2000 Sahara, 4.0, 5 spd
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post #24 of 33 Old 09-23-2021, 06:52 PM
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Quote:
Originally Posted by RH31379 View Post
I didn't check since I put the rebuilt ECM in tonight but prior to I was not getting ground to the ASD relay from the ECM. It seemed like all ground to the ECM were good but not ground signal out to trip the relay. I changed the CPS 1st when it 1st died. Assuming the ECM is fully functional since it was rebuilt what could cause high resistance in the circuit?
You used two words that do not work in diagnostics. I can say this with conviction because I have a 40+ year career and much of it has been spent in other guys bays figuring stuff out that they missed.

Your bad words are "seemed" and "assumed"...

I have been burned by meter leads that fail, backprobing something that is hard to do and less than reliable... ON and on and on. I have been burned more time by guys assumptions and what seemed to be right.

When I find a complicated failure I retest it several times in some instances.

Do you know how to test for a voltage drop?

If you cannot fix it with a hammer then it has to be an electrical problem.
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post #25 of 33 Old 09-23-2021, 08:25 PM Thread Starter
RH31379
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All ground had continuity to ground. So that's why I said :seemed" as for the ECM, I can only assume that it is good, the rebuilder said they replaced leaky capacitors and tested "ok".
Voltage drop? No. I have a multi meter and can measure voltages. If you can explain it I'm sure I can probably figure it out.

besides the 83 cj-7, also have an 87 yj, 6cyl., 5spd, weber upgrade, 6.5' western uni mount plow, also a 2000 Sahara, 4.0, 5 spd
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post #26 of 33 Old 09-24-2021, 06:44 AM
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Quote:
Originally Posted by RH31379 View Post
All ground had continuity to ground
Continuity is not the same as no resistance. “Any” connection will show continuity, but it may not have more than a milliamp of capacity.

Boojo should talk about the voltage drop but that’s how you test parts of a circuit for its ability to transfer power. Ohms is “a way” of doing the same thing but it has possibilities that aren’t readily apparent. Voltage drop tells the truth without math, other tools, or measured loads.

[size=3]Shackles & D-rings are different things.
Cranking IS turning over
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post #27 of 33 Old 09-24-2021, 01:46 PM Thread Starter
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Quote:
Originally Posted by Boojo35 View Post
A few quick things. It your check engine light comes on your ECM has at least basic power and ground. It really sounds to me like your control 85 /86 side of your ASD relay is the issue. Find the power side and make up a headlight bulb test light and test from that wire to ground. Then, test the ground side with one side hooked to the battery and then the ground side of the relay. Key on it should light for a second or two and then shut off until the engine cranks. It it does not light key on for a second or two you have high resistance in the circuit or a bad ECM. If it lights for a second or two and the does not light when you crank the engine you probably ( like 99.9%)have a bad crank sensor or wiring to the crank sensor.
I just reread this a headlight bulb test? never heard of this but I get the concept now that it would show excessive draw on the circuit. Can you explain this more? I agrees teh 85/86 is my problem. I was not getting ground out of ecm to pin 85/86 I was getting 12v. I will confirm again in the morning. But I think if you can lead me toward what is causing the no ground then that will solve the issue.

Thanks

besides the 83 cj-7, also have an 87 yj, 6cyl., 5spd, weber upgrade, 6.5' western uni mount plow, also a 2000 Sahara, 4.0, 5 spd
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post #28 of 33 Old 09-25-2021, 08:46 AM
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Quote:
Originally Posted by RH31379 View Post
I just reread this a headlight bulb test? never heard of this but I get the concept now that it would show excessive draw on the circuit. Can you explain this more? I agrees teh 85/86 is my problem. I was not getting ground out of ecm to pin 85/86 I was getting 12v. I will confirm again in the morning. But I think if you can lead me toward what is causing the no ground then that will solve the issue.

Thanks
It does not show excessive draw on the circuit, it puts an excessive draw on a circuit. It requires more current to operate thus loads the circuit better than an ohmmeter or continuity tester.

Your ASD relay will only have a ground to operate for a second or two after you turn the key on and then grounds again when the engine cranks and remains grounded if the engine starts. It matters how and when you test for the ground.

https://www.jeepforum.com/forum/f12/...ction-4354601/

Here is a thread from a while back that shows how to use a meter to read voltage drops and find bad wiring and connections

If you cannot fix it with a hammer then it has to be an electrical problem.
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post #29 of 33 Old 09-25-2021, 01:57 PM Thread Starter
RH31379
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I was able to find a ECM locally I was told worked and doesn't seem to make a difference.
Thank you for explaining the voltage drop test. I did the light bulb test and do get light from positive relay to ground but do not get a light at all when connected from positive battery to negative ASD relay when key is turned on. So unless I have to bad ECMs I think I need to start tracing grounds to the ECM and checking for voltage drops out front the battery.
Sound about right?

besides the 83 cj-7, also have an 87 yj, 6cyl., 5spd, weber upgrade, 6.5' western uni mount plow, also a 2000 Sahara, 4.0, 5 spd
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post #30 of 33 Old 09-25-2021, 02:41 PM
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Yes, you need to check the grounds and be sure that the wire ground wire to the ECM and pins from the ASD 85/86 is good.

If you cannot fix it with a hammer then it has to be an electrical problem.
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