Start circuit ideas
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Joined: Jan 2017
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Start circuit ideas
1988 F250 351w EFI
Can't get my truck to start. I have replaced the ignition switch, neutral safety switch, solenoid, starter, and ignition module on the distributor. Won't even attempt to crank. Any ideas?
Can't get my truck to start. I have replaced the ignition switch, neutral safety switch, solenoid, starter, and ignition module on the distributor. Won't even attempt to crank. Any ideas?
Lead Driver
Joined: Sep 2003
Posts: 7,018
Likes: 210
From: SoCal
First, make sure all connections are clean. I once replaced a battery, and the car got me to work, but would not start when I tried to go home. It turned out to be the battery terminal. A thorough scrubbing of the insides of each terminal with a wire brush made the connections much more reliable.
Then check the starter relay and motor. Will it crank if you try to short out the starter relay? There are two ways of doing this.
The more direct way is to take a jumper cable and short out the two large studs on the relay. This applies power directly to the starter. It may not make good enough contact to actually turn the engine, but you will know if the starter is getting power.
The other way is to short out the small stud that the ignition switch wire goes to against the large stud on the battery side. Some starter relays have two small studs, and I really don't know which one is for the ignition switch without trying. This will show you if the starter relay is working, and if it's delivering high current to the motor. This will allow you to keep the motor turning.
If neither of these methods cause the starter motor to turn, I would suspect the motor, or some connections to it.
Then check the starter relay and motor. Will it crank if you try to short out the starter relay? There are two ways of doing this.
The more direct way is to take a jumper cable and short out the two large studs on the relay. This applies power directly to the starter. It may not make good enough contact to actually turn the engine, but you will know if the starter is getting power.
The other way is to short out the small stud that the ignition switch wire goes to against the large stud on the battery side. Some starter relays have two small studs, and I really don't know which one is for the ignition switch without trying. This will show you if the starter relay is working, and if it's delivering high current to the motor. This will allow you to keep the motor turning.
If neither of these methods cause the starter motor to turn, I would suspect the motor, or some connections to it.
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