Starting gremlin that makes no sense

[Steelbuddha]

I can use ideas/advice. 1984 K20, 350 engine, SM465 manual transmission. In the last couple of years, I completely replaced the wiring harness(es) with the Painless 27-circuit retrofit, and it works great. (Just about everything electrical was also replaced -- new starter, solenoid, 140-amp alternator, etc.) Except: When the truck was freshly rewired, the starter would crank with the clutch fully engaged. Even though the clutch position switch on the purple starter wire has been physically removed and completely bypassed, the truck now demands that I push the clutch all the way in before the starter will crank. I've looked behind the dash, under the hood, and under the truck, tested all the wiring, and still can't figure out what's going on. You would think that if a wire was being impinged somewhere by the clutch linkage, it would be visible, right? I'm known for being a good electrical troubleshooter, but evidently not this time.

Any ideas about what I might be missing?

 

[legopnuematic]

If I were posed with this situation, I’d probably start by isolating the starter, wiring to starter, and key switch/column linkage.

-Remove trigger wire from starter and run hot lead from battery to trigger post, if it cranks like it should, that suggests the ground is ok and starter operation is as it should. If the starter does not crank when hot wired, check grounding or starter itself for some issue.

-Check trigger wire with a test light if it lights in the start position on the key, if it doesn’t, does it light with the clutch in? Isolating and working your way to the key switch and finally mechanically checking the rack for the ignition so on an so forth.

Where does your ground from the battery run to? To the frame? Block? Alternator bracket?

 

[waterpirate]

Here is your Gremlin.

How One of History's Dorkiest Cars—the AMC Gremlin—Became a Sales Success

Funny-looking and developed on the cheap, the AMC Gremlin was pure corporate brilliance.

www.motortrend.com

sorry, that there is funny!
Eric

 

[Ricko1966]

If I were posed with this situation, I’d probably start by isolating the starter, wiring to starter, and key switch/column linkage.

-Remove trigger wire from starter and run hot lead from battery to trigger post, if it cranks like it should, that suggests the ground is ok and starter operation is as it should. If the starter does not crank when hot wired, check grounding or starter itself for some issue.

-Check trigger wire with a test light if it lights in the start position on the key, if it doesn’t, does it light with the clutch in? Isolating and working your way to the key switch and finally mechanically checking the rack for the ignition so on an so forth.

Where does your ground from the battery run to? To the frame? Block? Alternator bracket?

Wonder if he's pulling engine ground through the Z bar? Check your battery cables make sure negative has a good ground to engine block,and if it has a temporary screw together battery terminal clamp that all the wires going into it are clean.

 

[Steelbuddha]

Wonder if he's pulling engine ground through the Z bar? Check your battery cables make sure negative has a good ground to engine block,and if it has a temporary screw together battery terminal clamp that all the wires going into it are clean.

Rick, the ground runs to the block, at one of the the alternator bracket mounting bolts. The battery cables are new, custom-made 2/0 copper with factory terminals. All body grounds are fresh. I just can't figure out why depressing the clutch pedal would make any difference when there's no switch in the circuit. Was hoping there's some peculiarity with Squares that I'm just not aware of.

Spencer, the trigger wire tests fine, through the ignition switch, etc. The screwed up thing about this is that everything tests as it should. I pulled the whole dash out again to make sure. And, initially, the starter cranked without depressing the clutch pedal, as it should.

Thanks for the ideas, guys.

 

[Ricko1966]

Rick, the ground runs to the block, at one of the the alternator bracket mounting bolts. The battery cables are new, custom-made 2/0 copper with factory terminals. All body grounds are fresh. I just can't figure out why depressing the clutch pedal would make any difference when there's no switch in the circuit. Was hoping there's some peculiarity with Squares that I'm just not aware of.

Spencer, the trigger wire tests fine, through the ignition switch, etc. The screwed up thing about this is that everything tests as it should. I pulled the whole dash out again to make sure. And, initially, the starter cranked without depressing the clutch pedal, as it should.

Thanks for the ideas, guys.

I'm wondering if the clutch Z bar itself is acting as metal to metal ground between the frame and the block when you put pressure on it. Check your grounds real well.

 

[Steelbuddha]

I'm wondering if the clutch Z bar itself is acting as metal to metal ground between the frame and the block when you put pressure on it. Check your grounds real well.

This looks like the perfect application for my Vevor articulating endoscope. I'll give you a report.

Thanks again.

 

[Ricko1966]

This looks like the perfect application for my Vevor articulating endoscope. I'll give you a report.

Thanks again.

I'd be checking with a multi meter.

 

[Bessie]

Just read this post, Probably too late but did you find it? I agree with the assumption that you have a ground problem, thats all it could be . Quick ck would be with pedal up ( in neutral ) turn ign. switch to start possition and slowly push the pedal down till starter motor energizes. I would start by pushing it slightly and slowly like an 1" then a little farther but stop and just move it up and down 1" each way and see. That way you are scrubbing a ground, nothing happens go a bit further, etc. If that's the problem, easy and quick. Good luck if you didn't already find it.

 

[Grit dog]

So it runs fine otherwise? Sounds like you have a Bluetooth clutch safety switch. That’s fancy. Lol

 

[Turbo4whl]

Look for a second switch located on the clutch push rod. GMT400's use this. Someone could have added this because the original switch didn't work. They fail too. Could have been stuck closed then all of sudden started working again?

 

[Steelbuddha]

Just read this post, Probably too late but did you find it? I agree with the assumption that you have a ground problem, thats all it could be . Quick ck would be with pedal up ( in neutral ) turn ign. switch to start possition and slowly push the pedal down till starter motor energizes. I would start by pushing it slightly and slowly like an 1" then a little farther but stop and just move it up and down 1" each way and see. That way you are scrubbing a ground, nothing happens go a bit further, etc. If that's the problem, easy and quick. Good luck if you didn't already find it.

Very late follow-up here, but the fix did indeed turn out to be improving the ground(s). Since the main ground goes to the alternator bracket, I removed the bracket and all hardware and cleaned everything. Taps and dies on the threads, made everything shiny. I also added a big ground cable straight to the frame from the engine ground. Starts as it should now. Looks like I just had some dirty hardware on a 42-year-old truck.

My main error was taking it for granted that the original grounds were working. Sometimes you just have to take *everything* apart and put it back together.

Thanks for the ideas, guys. Much appreciated!