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Dodge Repair/No start when check engine light doesn't work

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QUESTION: Hi - My 1995 Dodge Ram 3500 V10 has had cranking issue for a couple of years. It has always turned over, eventually, but sometimes it took a while.Gas tank sensor also slowly stopped working altogether. Last week it finally would not turn over at all. Took it to the shop, they said fuel pump. Replaced it, gas tank shows now, cranks beautifully. But.... now it is losing power at a slow idle, such as up the driveway and stalls and dies.It will re-start, but after several attempts,(when it stalls again) it will not turn over. But, once it is allowed to sit for an hour or so, it cranks right back up. I noticed that while it is in park at the idle, , if you turn the A/C on high ( a must in a Texas summer), it kills the motor almost immediately and the check engine light comes on.But then it starts right back up, at least 7 or 8 times, then we go back to the won't start til it cools off.
I took it back to the shop, but, of course it started right up there,lol.
But after fooling with it, I found that the A/C  on every setting but high is ok, but that last high setting kills the motor.and too many attempts at restarting it, makes it not turn over until it cools off.Any ideas what might be going on? Would like to be able to tell the Mechanic what it might be!
Thanks so much,
Laura

ANSWER: Hi Laura,
Because it is a '95 I believe that the engine control module has a self-diagnostic capability which stores fault codes in its memory which may tell us what the cause of the problem is. Try turning the ignition switch: "on-off-on-off-on and leave" doing that in 5 seconds or less elapsed time. Then watch the 'check engine" light, which remains 'on, to see it begin to flash, pause, flash, etc. Count the number of flashes before each pause. Then repeat the process to be sure of an accurate set of flash counts. Let me know the counts in the order of appearance and we'll go from there. I can list a number of suspects, but the fault code readout you will do may narrow us in on the cause.
Read the PS below.
Thanks,
Roland

---------- FOLLOW-UP ----------

QUESTION: Thank you for your quick response!
The truck is in a "cooling off"period again.ugh! When I turn the key, it will not
start and the check engine light does not come on. I went ahead and tried the key on,off,on, off, on, but, I got nothing. I think I will have to wait until it cools off so I can start it so the check engine light will come on.
When I can get it started, I will check to see if i can get a code (s) and post a follow up. Thanks again, that was an exceptionally quick response :)

ANSWER: Hi Laura,
I am surprised that the check engine light doesn't come on when you turn the key to the 'run' position without trying the starter motor. It does so in the car lines, so I thought it should in the truck lines, though I admit I don't have truck service manuals that go back to the 90's. If it doesn't, then this self-diagnostic approach may not be available. Then you might get a readout for free at a nationwide auto parts store, such as Autozone, of the garage you are going to would do that for around $40. They use a plug-in code reader for that.  They should have given that a try when you last went to them. In any case, try to get a fault code rather than having to rely on it failing when you take it in to them.
Thanks for the rating and nomination.
Roland

---------- FOLLOW-UP ----------

QUESTION: Hi Roland-
Yes,  I thought that was kind of weird that the check engine light wouldn't come on, too. But once it was ready to crank again, the light came back on.
I did get the truck started again. Did the key on, off, on, etc. The blinks were 1, pause, 2 pause, 5 pause, 5 pause. From what I saw on Dodge Ram info website for PCM fault codes, that just means the battery was disconnected, does that sound right to you, also?
That not the problem, for sure, lol.
What would you suggest I try next?
Thanks so much,
Laura

Answer
Hi Laura,
That code 12 is often disregarded in the belief that sometime in the past 50-100 starts the battery power to the engine controller was disconnected (which is what the code means) as part of a repair/troubleshoot action . But in this case I would suspect there is something to it, specifically that the fuse that connects the battery to the powertrain controller (which is what turns 'on' the check engine light) has a crack in its internal wire which 'opens' when it gets hot, and then closes when it cools down.
Unfortunately I don't have the wiring diagrams for the 90's truck lines but the fuse would be one of those in the engine compartment fuse/relay box. So what you could do is see if any of the fuses is labeled "fuel pump/ASD" and if so turn the key to the 'run' position so that the check engine light is "on", then remove that fuse to see if the light goes 'off'. If so you have found the fuse the powers the powertrain controller. If you can't find a fuse with such a label then simply try removing the fuses in that box one at a time until you find the one that turns the check engine light 'off'. Then look closely at the wire inside the fuse to note if it has a crack or just replace that fuse with the same size fuse. That may solve this situation. You were observant to note the check engine light wasn't working!
Let me know how this approach works out.
Thanks for the rating/nomination, both of which you may do again if you would like.
Thanks,
Roland  

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Roland Finston

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Get a Free Fast answer to your repair question about a Chrysler/Dodge/Plymouth car, minivan, SUV, or truck. Problems with electronically controlled engines and transmissions as well as body wiring problems are my specialty. This free troubleshoot advice forum helps you diagnose faults, minimize repair costs or do-it-yourself.

I answer questions seven days a week and respond to you in about 30 minutes. "Maxed Out" means I am answering another question or asleep overnight so try again later.

I have do-it-yourself experience (50+ years) and a library of 100 1982-2012 Chrysler factory shop manuals and 20 multi-manual Chrysler Corp. CD's.

I was voted "Top expert" from 2010-2015 here at AllExperts, and have answered 20,000+ questions.

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Five decades as a 'do-it-yourselfer' on domestic and imported cars

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Yahoo Autos Group called The Chrysler Lebaron Club (co-moderator)

Education/Credentials
Degrees in Physics/bruised knuckles.

Awards and Honors
"Top expert" of 2010, 2011, 2012, 2013, 2014, and 2015 here at Allexperts. Quickest "average response time" at Allexperts (currently no. 1).

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