Car Won't Start, Keypad problem?

[techmanagain]

A 2.5 TD being brought back to life will not start.
One fault(?) identified may give some guide to a problem inasmuch that the keypad only "pips" when No 1 is entered and never for any other number. The green light is singly illuminated permanently.
Any ideas if this is related to the non-starting problem?

[robertmnorton]

Hi Techman,normally the green light on it's own indicates the the anti-theft system is unlocked and you are free to start.The keypad inputs are acknowledged by the audible beep,failure to hear a beep would indicate that, that keystroke has not been received.This is probably a keypad fault,simply high resistance across the individual keys would be sufficient.If on cranking a continuous beep is heard, then regardless of the illumination state of the green light the anti-theft device is still activated and the red light should be on.Disconnecting the battery and reconnecting,then locking and unlocking on the plip may resequence the system, or an engine bay connector has been incorrectly mated with an adjacent one of the same colour.Please note this explanation is taken from a 2.1,but i would not expect it to differ on the 2.5
Good luck.
robertm

[noz]

Hi Techman,

With the keypad unlocked, 12v should appear at the stop solenoid on the injection pump indicating that the solenoid is open. Also, if its been off for a while you might need to pump diesel through to the injectors by using the manual pump on top of the fuel filter.

Cheers

noz

[xmexclusive]

Unfortunately with a 2.5 I do not think it is that simple.
The immobiliser routines are part of the engine ECU.
Even if you direct feed 12v to the stop solenoid or remove its plunger the engine has fuel but the immobiliser is still not bypassed so the ECU stays locked and does not operate the injection pump.
The ECU does not look for a single feed from the keypad but a sequence of four 12v pulses.
Got a silver estate in this state at the moment unfortunately.
Tried swapping everything I could think off.
ECU, keypad and double injection relay all work fine in another 2.5 of similar age.
(Identified 4 different ECU types so far, not all compatible).
All wiring checks ok, no shorts or breaks.
Keycode and green light are fine until you swap the bits back.
Using the components from the defective car singly and compleatly all work correctly to spec in the other XM.
Eventually got the silver car running by accident. Collected a job lot of recovered injection double relays from the local scrapyard and tried them one at a time.
Last one tried put the green light up permanently and the car starts.
Not all is perfect. The glow plug light is on permanently and the keypad beeps 4 times when you switch off. Occasionally most of the dash lights come on when you take the key out of the ignition and the engine stays running.
Can live with that for the minute as the brakes and ABS need sorting for the MOT.
The reason the Injection double relay made a difference was simply that it was a different type. Did not realise this until after I have tried it.
Had a couple of goes with the circuit diagram but still not sorted out what it is doing that is different.

John

This post has been edited by xmexclusive on July 10, 2010 06:58 pm