No crank issue

[fyre82]

My 2000 4.0 4x automatic, developed an issue a few days ago that has continued to perplex me.
I was driving home when the 'check gauge' light comes on. Temp gauge is high, not HOT. It goes down, light goes out, a couple of repeats of this I stop, check, and it definitely isn't HOT, coolant is full. I check the gauges a little closer and realize the charge gauge is reading low, about 25% instead of the normal 50%. After shutting it off when I get home, I won't crank, just 'clunk', all the lights go out until the key is released, all the other illumination, chimes etc are normal otherwise. It does crank and start with a jump, it gets to where I had to bump it w/900 amp booster to crank. Long story-short, battery replaced on warranty, on 2nd replacement alternator, new starter. Same situation, will crank with a boost, alt showed charge for awhile, then I got 2 clunks out of the starter. I have this result with a full charged battery as well.
Beyond parts here is what I have done
I get 13v at the battery, starter, alternator. Have checked for system shorts using the test light/pull fuse method and come up with nothing.
I've swapped relays and cleaned every ground I can find, even changed the single wire alt connection. I have come short of running another ground and hot to the starter.
So, what simple thing am I missing? I've, unfortunately, thrown about as many parts in there as I can.

Thanks
Rich

 

[Spott]

My 2000 4.0 4x automatic, developed an issue a few days ago that has continued to perplex me.
I was driving home when the 'check gauge' light comes on. Temp gauge is high, not HOT. It goes down, light goes out, a couple of repeats of this I stop, check, and it definitely isn't HOT, coolant is full. I check the gauges a little closer and realize the charge gauge is reading low, about 25% instead of the normal 50%. After shutting it off when I get home, I won't crank, just 'clunk', all the lights go out until the key is released, all the other illumination, chimes etc are normal otherwise. It does crank and start with a jump, it gets to where I had to bump it w/900 amp booster to crank. Long story-short, battery replaced on warranty, on 2nd replacement alternator, new starter. Same situation, will crank with a boost, alt showed charge for awhile, then I got 2 clunks out of the starter. I have this result with a full charged battery as well.
Beyond parts here is what I have done
I get 13v at the battery, starter, alternator. Have checked for system shorts using the test light/pull fuse method and come up with nothing.
I've swapped relays and cleaned every ground I can find, even changed the single wire alt connection. I have come short of running another ground and hot to the starter.
So, what simple thing am I missing? I've, unfortunately, thrown about as many parts in there as I can.

Thanks
Rich

If we assume the alternator and battery are good, then next we must investigate the wiring in the starting system.

Carefully examine all the main cables and connections between the battery and the starter, including ground cables. It is entirely possible that one of the wires or connectors is damaged, and cannot carry the high current necessary for starting, although it can easily carry the low current for accessories and operation.

It is common enough for wires to get damaged right behind the connector, where the rigid connector transitions to flexible wires and stress can concentrate.

 

[fyre82]

The battery and alternator are new and have tested good.

I need someone to turn the key/watch gauges etc. while I wiggle test. For some reason I have difficulty doing that solo...

I'm going through testing that I can do as well as cables.

Thanks

Happy Easter

Rich

 

[RonD]

Happy Easter

You can add a wire to the starter Solenoid, it is ON the starter motor, lol.

Smaller stud with smaller wire on it(yellow wire I think) and if you touch that added wire to Battery Positive starter motor will crank, regardless of key being on, so BE CAREFUL, block the wheels

So you don't need a helper

Test voltage at the battery when engine is cranking, should drop no lower than 9.8 volts

Starter requires high AMPs so you can't tell if a battery cable is good by just testing voltage.
I would replace Positive cable just on spec., it may carry voltage but can't carry AMPs.

Main Negative cable to the engine must also carry the same AMPs as Positive cable.
DC voltage needs a compete circuit.
Starter motor normally need 60amps, if either the Positive or the Negative cable can only pass 30amps then that is the max. amps available to the starter, so it can't turn over the engine.

Since you think alternator might be effected then Main Negative battery cable should probably be replaced, as starter and alternator share main negative cable but use separate positive cables.

If you want you can get a razor knife and a roll of electrical tape.
Slice back the insulation on the battery cables about 6" and look at the bare wire, if you see a whitish coating then wire is corroded and needs to be replaced, this is not a 100% test, wire can look fine for 6" but still have a bad spot.
Tape up the wire if you want to continue using it

 

[fyre82]

Thanks Ron, you are spot on as always.

I finally came to the neg cable suspicion after thinking about it all weekend.
I have a 5' cable so I just did a quick connection with that to ground. Off it went.
Upon examination there was a funky corroded connection under heat shrunk insulation. Cut it back a couple of inches, attached it to the terminal, worked fine so it's crimped, shrunk and final attachments are done.
Test drive to the hardware store, charging well and no hitches.

I think I can put the SOLVED stamp on this one.

Thanks to everyone that offered their wisdom.
Rich

 

[RonD]

Good work

Thanks for posting the fix