No voltage to starter solenoid wire

[jollyjerry]

I replaced the starter a few months ago. Truck decides to not start yesterday so I went through the usual suspects

* Battery was fully charged (12.6V across the terminals)
* No significant voltage drop when key held to start
* Positive wire to starter had continuity and showed voltage when checked against it's ground
* Starter solenoid and motor worked when connected directly to battery (I pulled it out to check)

I pulled the fuel relay so I could turn the key to start without pumping fuel. With the key clamped to start, the purple wire to the starter solenoid was not showing 12V. This makes me think the problem may be:

* Bad wiring. The plastic shielding around the wire had fallen off in several places.
* Bad ignition switch. I think this is ok because the gauges turn on, and the radio turns off when switched to start.
* Bad neutral safety switch. Haven't tested this yet, but wasn't seeing any codes thrown.

I wanted to check continuity on the purple wire, but it runs behind the engine and I think it groups into the main wiring harness. I plan to open up the steering column and test the output from the ignition switch itself, but wanted to try the easiest things first.

Am I missing anything?

 

[badazzbulldog]

check the fuse in the underhood fuse box its one of the maxi fuses

 

[badazzbulldog]

also the starter relay is in the same box

 

[jollyjerry]

also the starter relay is in the same box

badazzbulldog, thanks for the tips. Both fuses (IGN A 40A, IGN B 50A) were intact visually and when checked with a multimeter. I pulled the starter relay and I can hear it latch with 12V, and also verified that it's continuous when latched.

Next up is to figure out whether turning the key to start applies 12V across the relay. If it's not the switch, then it must be the wire. I'm thinking of running new wire from the fuse box since I can't get to the original wire easily.

 

[badazzbulldog]

here a quick test to try get a piece of wire with alligator clips on each end long enuff to connect on the solenoid connection at starter and follow the factory wire up from the starter and strip back casing at higher point and connect it see if it starts

 

[jollyjerry]

I did one better actually. I cut a short piece of wire and completed the circuit the starter relay is responsible for. Then I checked for continuity from there to the end of the solenoid wire. It looks to be good. The good news is that there's no short in the steering column, and the solenoid wire is intact. The bad news is something is failing intermittently. I ordered a heat shield wrap for the starter and some fresh corrugated tubing to protect the wire. Once that comes, I'll put everything back together and test again. Going to leave a lead wire out from the starter relay to make it easier to test that the next time it doesn't work.

 

[superdave]

One thing I would do is to take off all major electrical power and ground wires, clean them and the mounting point, and re-attach. Computer controlled vehicles are extremely sensitive to voltage and an iffy connection can cause a lot of problems.

It may not fix your problem, but it's free and may prevent another issue down the road.

 

[jollyjerry]

One thing I would do is to take off all major electrical power and ground wires, clean them and the mounting point, and re-attach. Computer controlled vehicles are extremely sensitive to voltage and an iffy connection can cause a lot of problems.

It may not fix your problem, but it's free and may prevent another issue down the road.

I've been doing that slowly, starting with the battery terminals, easy to reach grounds and connectors. I wirebrush/sand and then dab it with some thick grease. But you raise a good point about doing them together all at once.

 

[LOUDRNU]

Hey, not sure if these diagrams will be of any assistance...if not it was worth a try

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[jollyjerry]

LOUDRNU thanks! I figured out those pins with a voltmeter and with the diagram printed on the side of the relay. Bit behind in putting everything back together because it's been raining, but if it lets up tomorrow, I'll be ready to take it for a drive. Fingers crossed.