Re: Power loss after hard driving - sparks
Posted: Fri Jul 05, 2024 8:27 am
Re-reading your original post, you mention "reconnecting all the wires'. Generally, when a problem/symptom is presented as 'it's worked fine until I did this', my first suggestion is to revisit 'this'. In your case 'this' included the work connecting the wires. It's not clear to me exactly what was disconnected for the project, but I'd be looking hard at what might have been changed between 'worked fine' and now. Look for pinched or otherwise shorted wires as well as crossed connections.
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The starter in your pictures is different from the style I described for earlier 928 cars, so the warning about 'the other small connection' doesn't apply.
Unfortunately I don't have ready access to 944/951 current flow diagrams, so can't give you a specific diagnosis for your car. More generally, the trigger for the starter starts at terminal 50 at the ignition switch. For basic manual gearbox cars this would connect directly to the smaller terminal on the starter solenoid, also labeled 50. More modern cars add nanny functions like clutch-depressed switches to that circuit. For automatic gearbox cars, there's a 'neutral safety' switch in the circuit, often incorporated via a relay that somewhat simplifies the wiring. Look at your wiring diagrams and see what's between the ignition switch 50 and starter solenoid 50, and share back what you find.
-- If it's a simple clear path with none of the nanny/safety functions, it's simple to use your multimeter to look for continuity to 30 (battery positive) to that connection (either end) and see if the continuity remains after you release the key. Test with battery disconnected, trigger wire lifted from the solenoid.
-- The nanny/safety circuit additions make troubleshooting more interesting.
-- There's the possibility that the starter solenoid itself is damaged, and it's shorted internally between the starter motor contact and the 50 trigger connection to the solenoid. The safest check for that is a simple test with the starter out of the car, and booster cables attached to a battery. Trigger the starter by connecting the battery positive using a jumper wire or just a screwdriver to that trigger terminal 50. The starter motor should spin, and then stop when that jumper or screwdriver connection is removed. Same function as turning the key to start position then releasing it. If the starter motor continues to run, the problem is internal to the starter solenoid. Easiest solution then is to replace the starter.
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The starter in your pictures is different from the style I described for earlier 928 cars, so the warning about 'the other small connection' doesn't apply.
Unfortunately I don't have ready access to 944/951 current flow diagrams, so can't give you a specific diagnosis for your car. More generally, the trigger for the starter starts at terminal 50 at the ignition switch. For basic manual gearbox cars this would connect directly to the smaller terminal on the starter solenoid, also labeled 50. More modern cars add nanny functions like clutch-depressed switches to that circuit. For automatic gearbox cars, there's a 'neutral safety' switch in the circuit, often incorporated via a relay that somewhat simplifies the wiring. Look at your wiring diagrams and see what's between the ignition switch 50 and starter solenoid 50, and share back what you find.
-- If it's a simple clear path with none of the nanny/safety functions, it's simple to use your multimeter to look for continuity to 30 (battery positive) to that connection (either end) and see if the continuity remains after you release the key. Test with battery disconnected, trigger wire lifted from the solenoid.
-- The nanny/safety circuit additions make troubleshooting more interesting.
-- There's the possibility that the starter solenoid itself is damaged, and it's shorted internally between the starter motor contact and the 50 trigger connection to the solenoid. The safest check for that is a simple test with the starter out of the car, and booster cables attached to a battery. Trigger the starter by connecting the battery positive using a jumper wire or just a screwdriver to that trigger terminal 50. The starter motor should spin, and then stop when that jumper or screwdriver connection is removed. Same function as turning the key to start position then releasing it. If the starter motor continues to run, the problem is internal to the starter solenoid. Easiest solution then is to replace the starter.