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No Start Diagnostics 86 Comanche


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Hi there, my name is happyjeep and I reside here in San Fernando Valley and I own a 1986 Jeep Comanche Custom 4x2. I have a no-start condition and my fellow students and I diagnosed each components. Starter has been checked, and it's working, Relay is in operable condition, we were able to get feedback when the ignition from the key, and battery is fully charged to its specs. We're suspecting it may be a short to ground wire from Relay to Starter. If any comments or you may have experienced this similar problem, please notify me with your advice, so we can look into it and see what happens. To be Continued......

 

happyjeep

1986 Jeep Comanche Custom 4x2

 

P.S.: The truck is equipped with AMC 2.5L Fuel Injection and Aisin AX5.

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We have tested the starter and it works. This was done as a bench test. To clarify the feedback from the relay, I mean that I can get power from the relay, once I turn the key to KOER(Key On Engine Running). The main issue is a possible wiring problem from the Relay to Starter Solenoid. Yes, the vehicle has gas and spark works.

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:D Well now, happyjeep, you sound like an intelligent and eager young man. But you aren't likely to get any answers to your no-start problem until you answer the questions that have been posed to you. You seem to have a situation where the starter is not turning, otherwise you wouldn't be suspecting the wire from the starter relay to the starter motor. You still haven't explained what "positive feedback from the relay" is, but seem to imply that you have voltage when you turn on the key. You shouldn't have any voltage from the relay to the starter in a "KOER" situation, but only with the key in the "start" position. In any case you also haven't answered whether it's a cranking engine that refuses to start, or a "dead" condition when the key is turned to the start position(i.e. nothing happens when you try to start). If you don't have a cranking engine, how do you know there's spark at the plugs, and how do you know that there's fuel at the injector? You won't get either without the motor turning over. So if you can answer those questions that were posed before, then I'm sure someone here will be able to help you trace down the problem.

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  • 3 weeks later...

Thanks for the replies guys. I've taken all of these into consideration. For those of you who misunderstood how I explain the problem, I did my best as I can to be specific. I decided to look again at the wires, by testing them if any shortages may be found. Turns out none of the positive or the negative wires has any defects and detecting continuity in all positive wires to the starter and negative wire from starter proved they're intact. One wire to the starter solenoid that recives power to actuate the plunger from the starter relay was repaired because of a misdiagnosis by suspicion of frayed wires or shortage. That new wire will have to be reinsulated before the Comanche will leave the school shop. The final suspicion is the defected starter solenoid because of the intense heat it received from the postive wires when attempting to crank the engine. My instructor and I removed the starter, bench tested and it decided to give up totally and the whole starter burned itself out. I bought a rebuilt starter from the specialty shop my school referred to me at a low price, installed it last night and the Comanche was able to start and ran. The "No-Crank" problem is now eliminated from the problem. Look me up on the recent problem, the clutch bleeding.

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True to a degree, but when it comes to the defective solenoid, nothing seems to work. I've tried that theory and nothing happened. We had to use the DVOM or Digital Volt Ohm Meter, test light and remote starter to do the testing proceedures. I'm coming from a professional approach and I'm sure there are Jeep techs who are doing this professional approach, which may sound french, but it's a practice. Nothing personal.

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Wow........all this education talk is giving me a headache :ack:

 

Nothing wrong with doing all the diagnosis testing that you have already done.

 

So, the starter bench test OK........you don't have voltage to the starter solenoid??? I read that right???

 

So, us layman :dunce: would check the starter relay first.

 

:idea: But, did you pull the plastic loom off the battery cables to check to see if the cables are shot/corroded or insulation missing????

 

Sounds like the typical bad battery cables to me :hmm:

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