Hey fellas, long time surfer 1st time poster. Seein if anyone can help :Run down: Cat 242 00242CCMB00974 1,300 hrs. It has been sitting a little, came out to start-click-click-click. Threw it on the charger for 6-7 hrs. Click-click-click. So got a new battery hooked it up turn key to run- lights on panel, turn to start- 1 click nothing. Cycle back thru key no lights no nothing. I jumper'd the seat took the harness off start relay and checked and got 12.46 volts(red wire), then when I turn the key (voltmeter still on my 12.46 wire(red) the volts fall to 2.46. Any advice is greatly appreciated.
Welcome Natey. Well, there's 10v of voltage drop somewhere. Since you've bridged the interlock and figured out a way to test voltage while hitting the key start it shouldn't be too hard to find. - How's the earth strap looking below the rear window? - When you hit the key start, does the battery voltage across the battery posts drop to 2.46v also? If so the new battery's dead, look no further. Say your battery is fine, and you're getting a good 10v - 11v or so when hitting the start key... Stuff like this I usually clamp one DMM probe firmly on the positive battery post. Stick the other probe on the positive battery terminal, working your way along that cable all the way to the starter motor. Do the same thing with the - side of things... measure from neg battery post to its terminal, then along its cable to the battery isolator (if fitted), then across the isolator (turned on of course), then all the way to the chassis, then to the engine block, starter motor case, etc, etc. Always take the DMM reading when hitting the start key. Any cable or connection that reads close to 0 volts is fine. At some point you're guaranteed to find a voltage drop of 10 volts.
I'll send you an electrical schematic. You could probably use one.
Thanks for the Welcome Chrisso, I cleaned and Fluid Filmed all ground points (the rear below the relays/main breaker and the ground strap below the window) that I have stumbled across. I also took the liberty of removing the 6 relays checking ohm readings and running a bench test on each making sure they were not stuck and functioning properly. Me being me (little impatient, little bit farmerized, tiny bit reasonable) sez to myself apparently the key switch is functioning (ie or I wouldn't have 12.5 volts hit key fall to 2.5) so my next move was to uncouple the starter...so I did laid it on the ground, took my schumaker charger and strapped ground to case positive to post and proceeded to jump across solenoid on 12v 50amps and the starter slowly slid out and began a very slow methodical spin and tripped my charger. It is in transit to a starter/alternator shop(so I'll weigh those apples when I see what they tell me (rebuild or new). I hope this is my only problem but we all know how that goes. If you happen to have any other epiphanies or something I maybe should triple check by all means, I'm all ears. Thanks for your insight btw, I'm well versed in the 4 T's (if it's got tits,tires,or tracks-u got nothing but TROUBLES) and it always hold true. Thanks again Chrisso
Thanks Nige, A definite must, don't know if I like how you presented it "You could probably use one" it just doesn't give me that warm fuzzy feeling lol. But I shall study.
Well that's one way to test it. The other way was going to be in my next reply... the starter motor is the ONLY place you want voltage drop. I would explain but this video does it for me...
Excellent video explanation, good to have this on file. My A.D.D. kicks in and my lack of patience occurs and then can't seem to think clearly to find an answer to my problems thru the interwebs. Chrisso
All good Natey, as long as we get there in the end.