1997 Escort won't start, electrical I think.

krystlewv

4 door 1997 Ford Escort won't start. Won't/Can't jump. Tried to run hot wire and toggle switch to see if I had power. Didn't work. Starter went out, got new one and starter only clicks once when ignition is on. Have checked all connectors, fuses and wires. Battery and alternator are ok. When switch is on I got 12 volts at starter, when key is engaged to start it goes down to 3 volts at starter. Changed switch, didn't help. I have headlights, dash lights, all power. It just wont start. This has never happened before. It only happened after it got towed. I am a mechanic by trade 30 yrs but this has me stumped. I dont want to change the wiring harness, but will that help? All and all suggestions are appreciated. I feel like I have went over everything, a new view always helps.

PF_Flyer

Something is causing the voltage drop when the key is engaged to start. Looking at a schematic there are only so many places where it can be. The relay perhaps?