Cold Start Problem on Diesel - Please Help!!!!

[shaunlfc1]

Right hear goes....

Using multimeter we've discovered the following:

All wiring is fine, to and from relay, glow plugs and live feeds from battery and alternator.

12v's go into relay from feed, but nothing comes out either at GP end or at GP output on relay.

With ignition on we tested 5-pin connector, as one of these should give a reading of 12v's to indicate power going into relay and switching on relay/timer, but from all five connectors we got nothing.

So the issue seems to be the wiring from the ignition key to the 5-pin connector at the GP relay end? It seems the relay isnt getting told/power to switch on, to allow power to go to GP's?! Is this a correct assumption?

I dont think this will be a easy fix?

Can I not put in a manual switch from the dashboard, with ignition live wire, and still use existing 5-pin connector and relay and GP system? Rather then putting a whole new pre-heating system?

I was thinking if I cut the 5 wires from the relay, this disconnects it from the car's ignition, warning lights etc...... and simply put my own feed from a switch on dashboard, which'll turn on relay and send power from relay to GP's.

I hope my idea makes sense, not always easy to put down in words what one intends to do?

One last thing, somebody on another forum, mentioned about a coolant temp sensor caused pre-heating problems on his 405 he owned years and years ago, how do I check this, and where is it?

Cheers all......

Shaun

[Donaldiesel]

Hi Shaun,
If there is no 12v supply to the 5-pin connector when you turn the ignition key to the 2nd position, then you have found the problem. The terminals in the connector may be corroded, or the wire damaged somewhere in the loom. If you can't find the damage, a new ignition feed taken from fuse 12 should solve the problem. Make sure the new wire is securely tied to the loom to prevent damage from hot or moving parts.

The coolant temp sensor controls the postheater relay. This has an input to the preheater timer to vary the glow plug operation when the engine is warm. So a faulty thermal switch could possibly prevent the glow plugs working when cold, but you first need a working ignition feed to the preheater timer to find that out.

Don't cut the wires to the 5-pin connector unless you want to really screw things up. The ignition feed wire should be marked 'CC5'. There should also be a 12v supply to the 5-pin connector on wire '105' while the engine is cranking on the starter. Did you test the continuity of the earth wire 'M115'?

Regards,
Donaldiesel

[mart3442]

I think you have to bite the bullet and put the car in the hands of an auto electrician.
You've said yourself that you don't know what your doing, so..........