Intermittent starting issue

I have a 2005 Double Cab with the V6. I’ve had issues with it starting for about a year. (It’s an extra vehicle). Turn the key, and everything works as it should. Try to start it, and get nothing. Battery is good, cables look fine. Relay is new, fuses are new, ignition switch is new. Let the truck sit for two weeks, and it cranks right up. Next day, it cranks right up. Second day, nothing. Let it sit for a month, cranks right up again. All of this without ever moving the truck. Any advice on where I should look? Thanks!

 

Maybe the starter contacts are starting to go. May need either new or clean the brass contacts.

 

Did the problems start BEFORE or AFTER you did the prior work?

Did you use OEM or LAPS parts when replacing the other?

You had the battery professionally tested, right? You're not just throwing a voltmeter on it and seeing 12v+ and calling it OK is what I'm asking. Voltage and CCA are two totally different things.

Have you tried to jumper the starter relay pins in the engine bay relay/fuse box to bypass the starter relay when the truck won't start, just to confirm the starter relay isn't the issue? (note: On 1st gens, DO NOT buy generic starter relays, we've seen some shit here....)

If answers above are BEFORE/OEM/YES/YES, I'd start with testing your cables. They may 'look' fine, but other 1st gen drivers on here have found corrosion hidden inside the cables causing their issues. Also note this really fun issue we helped one guy find on here.

The two models of V6 don't usually have starter issues anywhere near what the V8 in these trucks do. While not totally exact to the V6 or your year, this thread may be interesting to you for troubleshooting steps. I assume it's not the starter relay, but this post has a video that covers diagnosing that in our trucks, again, not your exact year, but adapt the fundamental info to your situation.

Please come back when you figure it out so we get some closure here.

 

The issue started prior to any of the work I mentioned. The only thing I did prior was install a new belt as the old one had broken.

I have not had the battery professionally tested, but will just to rule it out. Figured that’s not likely the issue since it will start after it’s sits for two weeks or more.

I benched tested the relay, and it opened and closed appropriately, but purchased a new one anyway.

I’ll have to wait a few days till it won’t start again, then I’ll start testing all of the items mentioned.

Thanks blackdemon and shifty for the leads!

 

I agree with you on the battery: Doubt that's it. But sometimes troubleshooting a problem is not only about solving the problem, it's about removing variables. Parts store chains test batteries for free, why not rule it out?

Furthermore, to the 'problems inside the cable' I mention above. One guy here last month (@JasonC.) couldn't start his Ferd pickup. Similar situation. He found that if he wiggled the (positive?) cable while someone was turning it over, it fired right up ... he had a short inside his positive cable a ways down from the battery terminal. IIRC, it's a late 90s truck and he's in a non-rust-belt, low-humidity environment. You may try a similar troubleshooting step, since it costs you nothing except an extra pair of hands ... you jiggle the cables while someone kicks the key forward 1x per second.

 

Yeah my issue is a short inside the positive cable loom about a foot downstream of the battery. Thank God the windshield wipers were on when I jiggled it with the key in the “ACC” position. Radio came on too but volume was low. I recommend the wire wiggle test wholeheartedly. Just make sure you have something powered on that you can’t miss (like not lights or something, unless it’s night time).

 

+1 on the wiggle test.