Faulty Diesel Cutoff Solenoid?
Posted 05 January 2012 - 10:10 AM
After a little troubleshooting this morning I suspect the fuel cutoff solenoid has gone short circuit. Its' fuse has blown (if I've found the right one) and the resistance to earth is only a few ohms. If I connect a wire to it from the battery the wire gets warm and the place where it touches the solenoid glows red and smokes! Not good.
So, is it a big job to replace (the Haynes manual thinks not but I respect the views here more) and has anyone found a good supplier in the past?
Posted 07 January 2012 - 02:46 PM
Posted 07 January 2012 - 08:21 PM
I'm looking at the Haynes now and they seem to gloss over a few of the details Instructions are to remove the electrical connection (done) and unscrew the solenoid. However, there's very little wriggle room for a spanner in there and it looks like I'll have to remove the top of the fuel pump to get a socket on. Is anything bad likely to result from taking the top of the pump off?
can you get a socket in there? i am not familiar with were it is but i wouldnt go taking the pump to bits !!
Posted 07 January 2012 - 11:15 PM
Posted 08 January 2012 - 03:23 PM
Posted 08 January 2012 - 07:55 PM
Thinking a few possibilities first of all Fuse 14 feeds your stop solenoid via the engine ECU which in turn is fed from relay 109 (second layer in fuse box), this is where I would look first as they are prone to bad solder joints, the second is the engine ECU which is behind the instrument cluster and have heard reports of chaffing on the loom caused by the cluster rubbing through the wiring.
Am surprised you found the stop solenoid shorted to ground but not the cause of your non starting.
Posted 10 January 2012 - 10:12 AM
I unplugged the 3-pin connector that feeds the solenoid and fuel pump and attached a multimeter to the black/yellow wire that comes off fuse 14, and ground, set to audible continuity. The annoying beep meant the short was audible. I then gently moved wiring looms around until the beep/short cleared, eventually narrowing it down to the MAF connector, which is also fed from fuse 14. The wires at the connector were chafed and perished where it turns round a sharp corner at the connector end and the black/yellow was shorting to the adjacent, also chafed wire. A good clean and application of hot glue to the area should fix it for as long as I still have the car.
I can't believe I forgot my own golden rule - "It's always the MAF"!
Relays would have been my next stop but I couldn't think of a good reason why one would short to ground and blow the fuse.
The solenoid wasn't exactly shorted and was still operating when I attached it directly to the battery but was definitely drawing a lot more current than it should have, hence the sparks/smoke/glowing wire/three wasted troubleshooting sessions. Perhaps the ECU limits the current the solenoid can draw and so the solenoid wasn't the cause of the failure but it was definitely a bit faulty, just not completely ;-)
Posted 10 January 2012 - 01:36 PM
Glad you found it M8, reasoning behind relay 109 was as they suffer from bad solder joints there is always a possibility of shorting inside the relay when this happens, and as said all pump controls N75, N18, MAF etc all run off engine ECU so any short on any of these will cause F 14 to blow.
The wiring and insulation is known to be of poor quality and causes no end of problems especially in door and tailgete wiring.