Heater causing weird warning light faults?

Hi, bit of a weird one here that I can't find any info on!
Freelander TD4 late 2002
If I put the heater on the ABS light comes on the rev counter goes to zero & the temp gauge goes to the bottom!

It seems to do this if it's cold, but leave it running for a while & then the dials come back on & the ABS light goes out, but the TC & Hill decent stay on. It seems to help if the temperature is turned up too?!

If I turn the ignition off & back on it sometimes sorts the problem out. It rarely has a problem if I don't use the heater?

It's slightly random, but this usually what happens. I've got a cheap code reader, which says no faults can be found.

With strange faults like that, its unlikely a code reader will find faults - and even less likely it will find anywhere near the correct faults.

I'd say it is a wiring fault or maybe a fault in the circuit board on dash display - while the later may appear more obvious and does occur, I'm tending towards the former as the heater doesn't have an input to the dash display (or at least it doesn't have any indicators on there).

You might well be spot on! Just reading some other heater faults & someone mentioned a connector in the footwell by the resting plate. I've just unplugged it, sprayed switch cleaner on it & the fault is ok so far...!

Will see how it goes. THANK YOU!

Damn, didn't last long! Restarted the car later & all the lights back on again (with heater on). They flashed when I wiggled the connector though, but when I unplugged the fan the lights stayed on? Plugged back in & still on, so whether it's something to do with that connector I'm not sure. Will try & pull it apart perhaps.

I think I'd be looking at the ignition switch. Those are known to cause trouble on occasion, resulting in some odd faults.

Check that connector in the footwell again. Look closely at the pins and sockets as they can become dislodged from the body of the plug and get pushed back, resulting in no, poor or intermittent connection. Applies pretty much to any and all multi-pin connectors.

Ignition switch? I can put some WD40 down it, not sure what else to try?

Yes will have a look at that connector on the footwell again, that's my top suspect as it could have got kicked in the past. Thanks

Peter Cherry said:

Ignition switch? I can put some WD40 down it, not sure what else to try?

Yes will have a look at that connector on the footwell again, that's my top suspect as it could have got kicked in the past. Thanks

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The ignition switch isn't the key barrel - its a plastic switch that fits on the end of it - the barrel turns the switch. They are prone to failure, eg loosing contact while you're driving which emulates you turning the ignition off and cutting the engine - bit its possible other weird things might happen.

Weird things are also symptomatic of bad earthing points - which are often shared by multiple components.

Still not got to the bottom of this, I've inspected the heater connector & it looks fine, pins ok & I've lightly oiled it, etc. As soon as I turn the heater on the warning lights come on & the rev counter goes to zero. I've not inspected the ignition connector yet, but I'm thinking this is more to do with the heater than the ignition?
Does anyone know where the heater earths back to please? I'd like to clean that connection up.
Thanks all.

Lightly oiled the electrical connections?!?!

andyfreelandy said:

Lightly oiled the electrical connections?!?!

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Just a bit of switch cleaner...

Arh. That be ok then!

Peter Cherry said:

Does anyone know where the heater earths back to please?

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The ground points are at the bottom of the A posts, both sides. I'm sure the heater grounds on the offside A post.