95 g3500 no crank electrical issue (ignition switch?) - Diesel Place : Chevrolet and GMC Diesel Truck Forums
 
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Old 08-12-2014, 04:53 PM   #1 (permalink)
veggiev
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95 g3500 no crank electrical issue (ignition switch?)

Hi guys Ive got what I am hoping to be minor electrical gremlin to track down. Just as background info, Ive got a 95 g3500 with a naturally aspirated 6.5l db2 injection pump (no pmd). Anyways, In the past few weeks Ive noticed that when i turn the ignition, the "sensitivity" of the ignition switch has been decreasing a bit. Meaning that I am getting no response from the key turn except in one "sweet spot" where the vehicle will start. The vehicle would start fine once I hit the right spot and I got power to the starter.
Recently it has become extremely more finicky, and now the situation has deteriorated and my ignition cylinder seems to give me no response.

So heres what I know:

Key turned, I get power to my glow plug light, interior lights, radio. maybe to my gages. I can actually see the mph gage needle slightly twitch during the key turn, and the battery needle works, so i guess they work. But of course no power to starter.

Im not the best with electrical, but my initial guess was that my ignition switch was starting to go. Any thoughts? Loose ground somewhere? anything I can test to narrow this down further? Thanks in advance for any help fellas.


Last edited by veggiev; 08-12-2014 at 05:14 PM.
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Old 08-12-2014, 06:00 PM   #2 (permalink)
kerrye
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Could be. I have a little round ammeter I bought 40 yrs ago which lays on a battery cable and gives the amperage going thru the cable. It will tell you if the starter is drawing current with the key in the start position. If you have one and it is drawing enough current, it tells you the problem is in the starter and not the switch.

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Old 08-12-2014, 06:04 PM   #3 (permalink)
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This is the kind of meter I'm talking about. Induction Ammeter 2138 for Starter Current 400 Amp DC New in Box | eBay
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Old 08-12-2014, 09:10 PM   #4 (permalink)
Freddyack
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Test for the ignition switch: https://www.dieselplace.com/forum/63-...ml#post1608102

Another thing to check. The starter solenoid power wire runs near the passenger side manifold. Heat can cause a failure in this wire.

Always a good idea to check & thoroughly clean your grounds...and battery cables: https://www.dieselplace.com/forum/2755252-post5.html.
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Old 08-12-2014, 10:00 PM   #5 (permalink)
Glagulator
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Probe the CRANK fuse in the fuse block in the drivers side of the dash with a 12v. test
light while you try to crank it. If the light glows then power is headed to the starter, if not then you probably need an ignition switch. 1995 does not have a starter relay like the 96 and up do. The crank fuse does not feed the starter, it send power to the lift pump relay while cranking.
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99 CREW LONG SRW C3500 work truck 199k+ mi. orig. motor & trans 4.10, modded engine harness, new oil cooler & lines, all new front end parts and poly bushings, trans poly mount, all new brakes.
96 SUBURBAN K2500 wife's truck 210k+ mi. orig. motor & trans, 3.73...
95 C2500 Suburban 6.5td HO w/p, timing set, HB & pulley, all rubber hoses, modded engine & main harness, converted to OBD2, PMD to bumper...
95 C1500 Suburban 6.5td rebuild tranny, convert to DB2, replacing as many parts as I can.
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Old 08-12-2014, 10:15 PM   #6 (permalink)
Freddyack
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Quote:
Originally Posted by Glagulator View Post
Probe the CRANK fuse in the fuse block in the drivers side of the dash with a 12v. test
light while you try to crank it. If the light glows then power is headed to the starter, if not then you probably need an ignition switch. 1995 does not have a starter relay like the 96 and up do. The crank fuse does not feed the starter, it send power to the lift pump relay while cranking.
Added to the FAQs
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Old 08-13-2014, 10:34 AM   #7 (permalink)
veggiev
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thanks alot for the help fellas, im gonna jump into this today and see what i come up with. not sure if my 95 has a crank fuse because i have a mechanical lift pump, gonna see what i find..
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Old 08-13-2014, 10:57 AM   #8 (permalink)
Glagulator
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Just realized you have a van but should still have a crank fuse. Might be marked CRK.
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There are 10 kinds of people in this world; Those who understand binary and those who don't.

99 CREW LONG SRW C3500 work truck 199k+ mi. orig. motor & trans 4.10, modded engine harness, new oil cooler & lines, all new front end parts and poly bushings, trans poly mount, all new brakes.
96 SUBURBAN K2500 wife's truck 210k+ mi. orig. motor & trans, 3.73...
95 C2500 Suburban 6.5td HO w/p, timing set, HB & pulley, all rubber hoses, modded engine & main harness, converted to OBD2, PMD to bumper...
95 C1500 Suburban 6.5td rebuild tranny, convert to DB2, replacing as many parts as I can.
96 C2500 Suburban 7.4L converting to 6.5td w/ DB2, 4L80, 3.73
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Old 08-14-2014, 11:49 AM   #9 (permalink)
veggiev
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ok so thanks again for all the insights my friends. I finally got some time to poke around and I'm finding that:

I cleaned up and inspected all the grounds that I could find, especially the rear passenger manifold ground.
I cleaned up and tested the batteries, they are reading and looking good.
Ive tested the lead to the starter solenoid from the battery, and I'm getting 12v there.

Any thoughts on where to locate/test the ignition switch (switch end of my solenoid).

I know I can jump the switch on the solenoid and see if the starter kicks, but I'm working by myself with no jack stands, blocks, etc, and the starter is so hard to get at on these vans, it would be somewhat epic.

It would be great if I could move to ruling out/testing the ignition switch, plus i actually suspect this is where my issue is anyway, but of course I don't really know much about electric. I read the above link on testing the ignition switch but I'm not quite understanding it. Wondering exactly how to check for power at my ecm fuses?

I don't know if I made it clear before but my starter won't crank at all, and I have not been experiencing any stalling or things of the sort while the car was actually running.

thanks again all.

Last edited by veggiev; 08-14-2014 at 11:56 AM.
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Old 08-14-2014, 01:16 PM   #10 (permalink)
veggiev
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a quick update, i also checked my voltage on the switch stud (the small one) on my starter solenoid, with the key in start position. didn't get much on it. i put one lead on the stud and one grounded to the body (guessing thats right).. but anyway I'm assuming its supposed to have decent voltage when the key is in start position, don't know how much, but is this correct? and can i assume that if there is no voltage to this stud that my problem is probably in the ignition switch?


Last edited by veggiev; 08-14-2014 at 01:17 PM.
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