Strange electrical/starting problem

I have a C10 pickup (1985) that has been giving me problems and they now seem to be coming to a head. definitely electrical in nature. i was thinking that this was a straight-forward cap/rotor or some other issue but now I am leaning to a short somewhere in the electrical harness. The symptoms:

  1. First it just wouldn't start for me a couple of times after I had driven it a little bit then cut it off.
  2. Then after replacing or testing nearly all of the engine electricals the problem persisted and got worse. I couldn't even get it to start in the mornings although it would crank.
  3. Now it won't even crank. Battery = good, starter = good, Ignition switch = good. I did find what appeared to be a short between the switch and the starter. I got zero volts when I cranked. But when I bypassed this and got 10 volts at the starter I was only able to get the truck to start once. Most of the time it is still dead. Is there something simpler that I am missing a relay perhaps? What is the most efficient way to go and test for shorts? Any help whatsoever would be greatly appreciated.
Reply to
CarGuy
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I really cant help much but, you should exam all the wires to see if there worn down or swaped.

Reply to
kubbyk229

Let me get this straight, the truck will NOT crank using the key, but when you apply +12V directly to the starter solenoid it cranks. Correct?

Even when you get it to crank using the bypass, it's still a biyatch to get it to turn over. Correct?

When you were checking all the electrical leads, did you check the main positive wire that runs to the fusible links/distribution center? If the connection there is bad you'll have limited juice to the ign switch and ign coil, which could result in what you have described.

Doc

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Reply to
"Doc"

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classic ignition module failure mode

it gets worse

you;re saying only 10 volts at the big terminal of the starter ?

what is battery voltage ? if it's low, charge or replace battery.........you can't troubleshoot without haveing full power available

sounds like a REALLY BAD connection somewhere

check:

battery volts

turn on headlights, check frame to battery negative, should be '0', if so, negative cable and connections are good

turn off headlights, turn heater blower to HI; check between battery positive and big terminal on starter, should be '0', if so, battery positive cable and connections are good

if you find any voltage on the above two checks, start narrowing it down, for instance

say you see 6 volts between battery negative post and frame; check between frame and the actual cable (poke a probe thru the insulation, you can always wrap tape around the hole)

if that reads '0', then check actual battery post to cable

keep narrowing your 'field of view' down till you find it

Reply to
TranSurgeon

Oh I forgot to mention when I crank and turn on ALL lights lights stay on but when I turn on the heater and then crank the heater dies. Yes 10 volts between ignition switch and starter which the OEM manual said anything above 7 volts is good.

Reply to
CarGuy

yes.

yes.

And yesI check the main junction block. I have followed the test procedure directly from the OEM manual and that was one of the tests.

Reply to
CarGuy

normal, any device controlled by the ignition switch ie, blower fan, radio, etc will not have power when cranking, this provides more amps for starting the vehicle.

Have you checked the neutral safety switch? Assuming it still wont crank when asking this.

Whitelightning

Reply to
Whitelightning

No but i will check thanks. what about any relays? Are there any I need to check and how do I test these?

Reply to
CarGuy

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