My starter on my 1996 Daimler Century 4.0 Auto runs all the time when you turn the ignition on to position II.
Once started moving the selector away from P disables the starter so the car can be driven but as soon as P is selected again the starter cuts in.

I have been told to look at the glass fibre insulated wires that run to the starter very close to the exhaust for a fault or it could be a fault with the gearbox inhibit switch below the gear selector shaft on the side of the gearbox.

Any thoughts appreciated.

KR
Charles

 

The first thing I would check is the actual ignition switch. I suspect it is faulty and providing a start signal when in position 2.

The RW wire should be grounded in position 3 only. If it is grounded in Pos 2 then the fault is likley in the switch or the wire could be shorted to ground between the switch and the BPM (Body Processor Module). The fault may also be internally on the BPM.

The gearbox rotary switch only provides an inhibit function so you can only start in P or N - it does provide a start signal so I'm very doubtful that would be you issue.

 

I would agree with the diagnosis that it is most likely the ignition switch

 

I have changed the ignition switch for one off a spare column and BPM and the fault is still there. (First changed switch & then BPM so neither made a difference)
I will check for earth faults on the RW wire and try another engine ECU as that is also involved in "cranking"
This is a frustrating one!

 

Having further studied the wiring diagram the "Earth fault" I think has to be between the ignition switch and the BPM or between the BPM and the P/N inhibit switch on the gearbox. I will look into it further tomorrow as it is 21.46 UK time and dinner is ready!

 

I have done the following
Cut wire 33 RO from P/N inhibit switch at BPM
Cut wire 41 RW from ign sw at BPM
Cut wire RW at ign sw
Disconnected BPM completely
In all above scenarios car still starts
Conclusion earth fault must be between BPM and P/N inhibit switch.
Should have realised that at step 1 !!
Now to find switch

 

There are 2 multi pin connectors to the N/S of the gearbox. Disconnecting either one of these stops the starter spinning in position 2.
One set of wires goes to external position sensor switch the other goes to a multi pin connector on the gearbox itself. This is not looking good.

 

Problem solved
The car had been standing for a while
Water had entered the position switch on the side of the gearbox due to jacking corrosion at the flange.
After several red herrings I finally worked out what had happened.
The corrosion had restricted the movement of the wiper arm within the switch from moving and it had bent before coming free. It is an injection moulding which incororates two bus bars made of stainless steel. One of these had bent and was touching the other causing a short. It was not possible to staighten it as it is retained within the injection moulding. I cut away enough of the material with a miniature cutting disc and a dentists drill to recreate the gap between the two bus bars. The fault has gone and all is well. The rubber seal had been distorted by the corrosion rendering useless so after carefull cleaning of the slot and the rib that presses on the seal i reassembled the whole thing with silicon. That is how the cable entry is sealed anyway.