Starter Motor Runs On

[Phil Gti 11]

I replaced a faulty starter motor with a new Bosch unit. It started first turn of the key a few times without issue. The last two occasions I have attempted to start my car and the starter motor won't disengage, I have taken the negative battery lead off, waited for a minute. Then reconnected it and continues to spin. I made sure the electrical connections on the starter motor solenoid weren't touching. I tried hitting the solenoid with a mallet.

 

Can anyone tell me what I am missing?

[j_turnell 137 3 Cars]

Could well be a faulty ignition switch/barrel.

[Phil Gti 11]

Oh : ( it's one thing after another. How do I test this?

[Phil Gti 11]

I have searched the forums but unfortunately my grasp of electrical work is basic at best. I expected a relay to be faulty or a bad connection. Can anyone tell me what and how I need to test as the usual things I have tried have left me scratching my head!

Edited September 21, 2015 by Phil Gti

[dobboy 231 2 Cars]

Try taking the small wire off the starter and reconnect the battery, get someone to turn key and flash small wire to solenoid, and try fathem out if solenoid disengages?

 

It would maybe help rule out a dodgy/sticky solenoid?

[Phil Gti 11]

I can hear when I connect and disconnect the battrery lead that the solenoid is not moving back into the rest position. It seems there is a permanent live to the motor. I need some detailed advice on what next and how pls

[welshpug 1,737]

Get a multimeter, check the voltage on the solenoid wire.

 

if it stays live theres a short in the wiring or most likely a worn out ignition barrel, check at the starter, then work back to the ignition.

[dobboy 231 2 Cars]

an easier way might be for you (if you don't feel confident electrically) is to remove the starter, strap a VE- wire to it, wire a feed to the motor, and flash 12v to the solenoid and then you can determine that your starter/solenoid is disengaging ok or not.... (I wouldn't rule out a dodgy solenoid if it's a replacement starter if everything was ok before you swapped it...... I assume you've connected it right?

 

Or do as WP says regarding the smaller solenoid wire.

 

You could maybe also find the starter/solenoid wire under the steering wheel/brown multiplugs, (using 16v conversion wiring guide to identify the wire), and see if the 12v drops out when the key springs back..... then you'll narrow down where the problem is.

[Ozymandis 104]

Put a bulb on the small terminal and if it stays lit, get a new ignition switch, doubt its something shorted to that circuit.

[Phil Gti 11]

I read a post about a member from the forum who eventually found out what was wrong with his car. He traced a very small amount of power earthing out from the S.A.D sensor electrical connection and this caused a permanent live to the S/Motor. The fix he used was to rewire some of the loom adding a relay too. I am not happy about that.

 

I followed his instructions to test. I removed the electrical connection for the S.A.D sensor and reconnected starter motor wires and battery negative lead. I started the car first turn of the key and the motor disengaged!

 

I am going to see if it happens again now I have reconnected the S.A.D sensor and hope it was just a sticking solenoid in an unused new starter motor and now it will be fine

Edited September 23, 2015 by Phil Gti

[welshpug 1,737]

a plausible explanation, its not a sensor btw, its a supplementary air device, quite a simple slow moving valve controlled by a bi-metallic spring.

 

it has a heating element, and is also bolted to the thermostat housing, it will still close without being plugged in, just takes longer.

[Phil Gti 11]

Well spotted that was a typo errorrrr.

 

I understand how it works and its purpose. I didn't fully understand how this earthing issue could cause the starter motor issue. I will go to my garage tomorrow and try starting it a few times and fingers crossed it was a glitch

[welshpug 1,737]

its a quirk of the wiring, I think the starter solenoid is also connected to the sad for some reason, so possible that an issue with the wiring there or the valve itself could cause it