Electrical problem please help

[mchater]

Hi everyone,
I’ve just picked up a 2008 SDI caddy that been stood for a year. I have a few electrical problems which may all be linked to a typical fault that I hope someone can point me in the right direction so here goes....

I have replaced the battery, I have checked all fuses, I have cleaned all the under bonnet earth points but these are still what I’m up against:

1, 9/10 the remote un locking will not work, nor will the switch on the door operate the central locking
2, 9/10 it’s difficult to start, sometimes I have to crank for ages as if no power to glow plugs,or waiting for fuel to be drawn up from tank, sometimes the starter motor turns really slow as if battery is flat, sometimes it’s starts perfect
3, engine management light is on

I have the following fault codes:

Engine;
P0118 coolant temp sensor signal too high (I have replaced the sensor)
P3102 intake manifold flap no signal
P0403 egr malfunction

Instrument cluster;
Function limitation due to under voltage

Terminal 15 electrical problem in circuit
Ignition switch D terminal S electrical problem in circuit
Ignition switch D terminal X electrical problem in circuit
Ignition switch terminal P electrical problem in circuit
Ignition switch D terminal 50 electrical problem in circuit

Any ideas? I’m thinking ignition switch replacement next...

[mchater]

Ignition switch has now been replaced and still the same faults....

[Doc]

The ignition switch faults can often be just simple batter condition problems like under voltage while cranking.
Try sort the engine faults first to make it start better and then the ignition fault should sort itself due to less cranking.

Have you done and investigation into the wiring for the three engine faults? Often there will be wiring harness failure rather than an actual sensor fault.

[Sommarstrom]

I had some strange engine faults on my Caddy and it was also difficult to start sometimes, that was because of a bad cable between chassi earth and engine earth.
You can check it with a volt meter, should be 0V dc.
I had almost 1V when i measured mine with the engine running.
You can also try if it starts better with a jumper cable between chassi and engine.