Dispatch 1.9 TD Temp Gauge

[Deequeue]

Hi All,

I've had a dig through the forum, but I've not managed to find anyone with the same issue as I have on my dispatch - its a 2000 reg 1.9 XUD.


The temp gauge on the dash is constantly off the hot end of the scale, even with the ignition off, although the little red warning light does come on with the ignition, and extinguishes when the engine is started. The fan sender is working correctly, and the fan itself operates when the 2 outer pins in the connector are shorted - The van cooling system heats up correctly, the heater works fine too - so I don't think its a massive issue.

I've since managed to find that the gauge itself gets its reading from a sender on the thermostat housing, but there are a pair of senders on there, one with a blue connector, one green. I'm guessing one supplies the light, and one the gauge, but I have no idea which!


So - can anyone tell me what the senders do, is there any way of testing them off the van - or disconnected from the loom - and do you think the gauge may actually be the issue? I assumed the one driving the gauge should be a resistance based sender?

I'll be extremely appreciative of any assistance - the gauge off the end is a bit disconcerting.


Thanks
Dale

[citroenxm]

The GREEN gives the TEMP Guage, the Blue other info.

OFF the guage useually means a DEAD short somewhere, wheither its in the Green sensor (Incidentally its Common to ALL PSA cars with a temp guage) or the wiring harness has a short in it, prehaps under the bonnet due to wire insulation breakdown from engine heat..

[Deequeue]

Perfect - thanks for the info - that will definitely help me get to the bottom of it


I'm getting infinite resistance across the 2 pins of the sensor that's installed in the van - is there a specific way to test these sensors that doesn't just involve chucking a multimeter across the terminals, or is it definitely goosed?

One other thing - is the gauge driven by the ECU, or could I potentially just run a circuit to the back of the gauge to test it?

[citroenxm]

I'm certain which way but my guess is open circuit when cold to indicate fans off and as it warms up a lower resistance as it warms up.

[Deequeue]

The fans are run from a separate sender that sits in the rad - I pulled that one and tested it last night, that was also when I figured out there's more than one temp sender on the unit.

As you say, that one is open under 90 odd degress, and completes the circuit above.

Long as it just drives the gauge and its not a feed to the ECU i'll run a pair of wires to the back of the gauge and see what I get