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Old 05-22-2009, 05:18 PM   #1 (permalink)
oldred95
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some new info on the starter engage issue

This seems to be more of a first gen d max thing so I will post it here. We had an 04 come in at work with an intermittent no crank sounded liking it was grinding the flywheel noise. Found nothing physically wrong, starter and flywheel were in good shape. Finally after a call to tech assist we learned that between the battery that supplies power to the under hood fuse block and the starter solenoid, it was dropping 1 volt across the entire circuit. From the battery to the fuse block it dropped half a volt and from the starter relay at the fuse block to the starter solenoid it dropped another half a volt. GMs fix is to replace the under hood fuse block which runs in the neighborhood of 400+ dollars but it did fix the problem.

My dads truck has had this problem since he got it last fall. We've tried countless starters and even a fly wheel with no real luck. The current starter acts up maybe 4-5 times a month. I am going to try a Ford (i know the F word) starter relay and see if it helps anything. Basically the original starter relay in the under hood fuse block will stay put and just turn the ford starter relay on which will be mounted close to the starter, probably on the firewall. A heavy gauge wire will run from the battery to the ford starter relay, and then when its switched on another heavy gauge wire will go to the small wire at the starter solenoid. This should provide a solid 12 volts everytime and eliminate the voltage drop. Its worth a shot if you are at wits end.
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Old 05-24-2009, 03:14 PM   #2 (permalink)
Tolliwacker
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Old 05-28-2009, 11:19 PM   #3 (permalink)
oldred95
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The old mans truck had been starting great until I showed up today and then it acted up. I heard it hit and engage and then slip out as it started to spin the starter. Started fine after that but I went ahead and put a relay on it like planned. I used a John Deere 30-50 series starter relay (Ford starter relay minus the "I" terminal). I had to enlarge the holes slightly but the relay slipped right onto the studs at the firewall where the rear of the battery box bolts to the firewall. Its a nice location, out of the way, not too obvious and centrally located for this retrofit. Then I ran 10 gauge and soldered connections from the battery to the relay, 10 gauge from the relay to the solenoid, and 10 gauge from the relay to the original purple wire that went to the starter solenoid (energizes relay) because the original purple wire was not long enough to reach as is. I simply used an eyelet on the 10 gauge wire and a screw and nut to bolt it to the eyelet of the purple wire since I didn't want to cut anything in case this didn't work and needed to revert back. I started it several times in a row (which is when it would act up before) and it started perfect everytime. Only time will tell but according to tech assist ridding the voltage drop will fix it.
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Old 05-29-2009, 11:03 AM   #4 (permalink)
RonJT
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Nice Job! Does anyone know what the current draw is when the solenoid engages? Maybe GM simply underestimated the voltage drop running that much current and did not properly size the wire?
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Old 05-29-2009, 11:39 AM   #5 (permalink)
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not sure I understand why you did it that way, and Im also not sure what you did will fix anything...

The relay in the UBEC is from the ECM (yes, ECM, no such thing as an ignition switch actuating the starter on these truck) to the starter solenoid. All the relay does is energize the solenoid. It doesnt take much to energize a solenoid, so even if you are getting a loss of voltage to the starter solenoid, as long as it energizes, you are still getting the full battery power from the battery to the starter...its not like the solenoid (not the relay) can only "half engage" (because it got only 9 volts from the starter RELAY, for example) and give less than 12 volts to the starter......

I guess what Im just saying is Im completely lost as to your diagnosis and fix for this problem.

ben
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Last edited by DURAtotheMAX; 05-29-2009 at 11:39 AM.
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Old 05-29-2009, 11:16 PM   #6 (permalink)
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Quote:
Originally Posted by DURAtotheMAX View Post
not sure I understand why you did it that way, and Im also not sure what you did will fix anything...

The relay in the UBEC is from the ECM (yes, ECM, no such thing as an ignition switch actuating the starter on these truck) to the starter solenoid. All the relay does is energize the solenoid. It doesnt take much to energize a solenoid, so even if you are getting a loss of voltage to the starter solenoid, as long as it energizes, you are still getting the full battery power from the battery to the starter...its not like the solenoid (not the relay) can only "half engage" (because it got only 9 volts from the starter RELAY, for example) and give less than 12 volts to the starter......

I guess what Im just saying is Im completely lost as to your diagnosis and fix for this problem.

ben
Its not my diagnosis, its GM engineerings diagnosis. I know how the starter solenoid works and I don't really know how many amps it pulls but I would say in the 10-15 max range. The only thing I can figure is at random it doesn't have quite enough voltage/current to keep the solenoid held in and as the starter disengages it grinds the flywheel as it spins down. All I did was use the stock purple wire to the solenoid to turn on a seperate big heavy duty starter relay thats mounted to the firewall that puts a consistant solid battery voltage to the solenoid when the key is in the crank position. This is the more realistic fix to what GM said to do which is replace the UBEC. Evidently through the countless connections and 10 or so feet of wire it occasionaly drops enough voltage it doesn't start all the time. So far its working perfectly.
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Old 05-30-2009, 09:55 AM   #7 (permalink)
keith_2500hd
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most electronics have protection circuit that shuts down when voltage goes below 10volts to prevent killing ecm/pcm's.
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Old 05-31-2009, 07:28 PM   #8 (permalink)
oldred95
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Bad news. 2nd day with the relay added on it made the grinding noise again. It was worth a try but it still has got to be the starter itself causing the problem. I don't know why technical assistance said this was the fix since like you guys said the solenoid either won't work if the voltage isn't right but for whatever reason it seemed to fix the truck we had come in at work with the same sort of issue.
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Old 05-31-2009, 08:03 PM   #9 (permalink)
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I had a similiar problem when the batteries were almost done ( for lack of better words) about a month later I changed the batteries.
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Old 05-31-2009, 10:19 PM   #10 (permalink)
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yep...I was almost positive techline's fix wasnt going to do anything.


when you replaced the starter, did it come with a new solenoid? Or just the starter itself and you reuse the original solenoid? Are the dmax starters solenoid-shift?

ben
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