I have an electrical problem I can't figure out. I came out one morning and when I tried to start the truck, the solenoid clicked, but no starter. Also, all the electronics shut off until the battery was disconnected and reconnected. Since then, I've replaced the starter and tried a different battery. When I go directly from the positive terminal of the battery to the hot post on the starter, there is a spark but no turning of the starter and immediately the voltage drops to 4 volts. I can measure 12+ volts directly on the terminals of the battery, but the rest of the system measures ~4 volts. The ignition switch, relay, and solenoid work correctly. The motor turns normally by hand as well as all accessory pulleys. The old starter turned fine when connected to the battery directly, once out of the vehicle. It acts like there is a faulty circuit breaker that trips as soon as the load of trying to turn the flywheel is applied. The truck starts and runs fine when push started. What am I missing? Is there some kind of electrical overload protection somewhere? Thanks for any help.

 

Suggest to inspect and to clean your connections. Don't forget about the grounding connections - battery-to-block and battery-to-frame/body.

There shouldn't be any circuit overload devices in the starter motor loop. Another possibility is that the contacts in the starter relay are burnt, but really doesn't explain why the accessories are seeing only 4 volts.

 

I totally agree with WDE on this one. Sounds like a bad ground to me. Also might look for corrosion down inside the wires from the batery. Cut a small slice in the protective cover of the battery cables and look inside.

 

Something to try. Turn on headlights and beep horn. While doing this engage starter. If lights and horn remain on, solenoid clicks, the problem is in the starter or the wire from solenoid to starter. If horn and lights quit working the battery is at fault or wire from batt to eng block. This simple back yard mechanics trick has worked for me on aircraft, cars, trucks or what ever.

 

Aircraft with horns?

 

i think if theres an airplane comming at you a horn wouldnt be necessary for you to move out of the way

 

OK, you comedians! FYI aircraft do have horns. How about a stall warning horn? How about a landing gear warning horn? I do admit these low current draw devices won't help with the troubleshooting on aircraft but the landing lights will. The simple test works in determining if the problem is at the power source or at the working end. Anyway its nice to see people are reading the replies. Back to the originator, if I read you correct, you have 12 volts at the battery and 4 volts at the starter. If you have 4 volts at the starter side of the solenoid, that means you have a voltage drop of 8 volts at the solenoid. Way out of limits. Could be your problem.

 

Thanks for the help, everyone. It turned out to be a bad connection. I cleaned both the positive and negative connections where the wires go into the battery terminals (recently replaced with aftermarket) and that fixed the problem. I was surprised to find that really the only ground for the whole truck is connected at the starter. It does look like there's a small ground connection for the electronics in the cab, but all the rest goes to the middle bolt on the starter.