Electrical grimlin

Hey guys... had to have my truck towed home the other night. The problem began last month after a good rain came through. I tried to start it up and nothing happend, no clicks from the starter or anything else. Minutes later tried again and it started with no problems, this went on intermediatly till last night.

The battery check out fine 12.7 at autozone on the machine, though under crank it jumps down to 5. The starter is a newer Green machine within 6 months. Symptoms are no start, my relay checked out, bought a new one to be sure and no change.. I do get clicks from it when I attempt turn over. Turning the key to the ON position my interior lights and dash lights come on slow when i crank lights go out aslo when I press the brakes in the on position they all go out only to come back on after releasing it.

Ive disconnected all accessories from the battery, checked those wires and from the stereo and amp. Im thinking a bad ground somewhere? But if yall could help with some other diagnosis it sure would help.

 

I <3 electrical problems.

Some voltage drop is ok during cranking, that seems excessive though.

Relays usually dont go out intermittently.

Battery should charge to near 14v when full.

So the starter uses the engine ground, i would suspect other ignition issues if this was the case, but check the ground point/cable anyway.

A difference in voltage drop from B+ to battery ground during cranking, and starter + to battery ground during cranking of more than 0.6 volts indicates an issue.

I would confirm the battery is good first. Otherwise Im thinking its either a bad connection to starter, or you got another starter with a bad solenoid. If you were in California, i wouldnt even bring up the former, but im assuming you get snow and road salt up there.

This is a good guide i like to refer people too. Also can you please add your truck to profile, i was going to look at the wiring diagram but dont know what year to look at.
http://www.aa1car.com/library/voltage_drop_testing.htm

 

I went thru that same hell with my truck for almost a year, battery was good,alternator checked out fine, I too thought about it being a floating ground, even went as far as replacing both primary cables for starter & ground.

With the voltage/amperage drop you mentioned is a red flag pointing towards the starter (even if it checked out fine before) I'm thinking internal fault with the regulator/starter thats what mine turned out to be....

 

So, got it fixed. Ended up being the battery. Took it to autozone, they tested it and said it was good. This morning I took it to napa they said bad, which I thought also because of the 5amp at crank. Took it back to autozone and they tested it again only to say it was good. So frustrated at the time I went home took the battery out of my camaro and hooked it up BAM truck started right up. Stupid autozone! It was under warranty so I returned it and had the cost charged to a Optima yellow. Thanks for the help fellas.

 

that much voltage drop during starting is NOT ok... i've personally tested about a hundred batteries using various equipment while working as an auto tech for over 7 years. the only voltage drop you should get is from ~12.7v to ~12v while under load. . down to 5 volts means you have at least 2 dead cells.

 

and keep in mind, you can get 8 AA batteries in series and confuse those vatozone guys cause it shows 12v.. also, sorry i didn't get to you sooner about this :\