Water temp guage stopped working

[shorty123]

Hiya, recently had my car serviced by TVR bodyshop nr Bristol, they did a great job, car runs better than when purchased... but a day later the water temp guage stopped working, i noticed the needle moving eratically as if the electrical connection has been lost, Does anyone know how easy or hard it is to get to the back of the guage so that i can check the connection? b4 i start flailing around removing dash assembly's!

Ta - Shorty

[mick_coupe]

Probably easier/best to check the sensor first..before you take the dash apart!

Mick

[GreenV8S]

Try to eliminate the easiest options first. A wiring fault is the most likely cause (especially since it worked erratically before it gave up) and the wiring out by the sender is very vulnerable. It might be as simple as a loose connection to the sender. Failing that it could be a faulty sender, or a wiring fault inside the car, or a faulty gauge.

[shorty123]

GreenV8S said:

Try to eliminate the easiest options first. A wiring fault is the most likely cause (especially since it worked erratically before it gave up) and the wiring out by the sender is very vulnerable. It might be as simple as a loose connection to the sender. Failing that it could be a faulty sender, or a wiring fault inside the car, or a faulty gauge.

Hmm i havent got a bible... dare i ask where the sender is located, im guessing its not the sensor that is at the bottom of the alloy expansion tank... ive looked in this area and all seems ok at the mo, i notice a small sender that is tapped into the inlet manifold near the plenum, is this the one?
Help greatly appreciated.

Shorty :-)

[GreenV8S]

shorty123 said:

dare i ask where the sender is located

It's screwed into the inlet manifold, high up on the front of the engine. Follow the top hose back to the thermostat housing at the top of the engine, find the casting that the thermostat housing is bolted onto, you will find various bosses here and two of them will have coolant temp sensors screwed in. The sensor with a single wire drives the gauge. (The other one is used by the ECU.)

Apparently some cars have a sensor on the end of a short pipe rather than screwed directly into the manifold, but I haven't seen this arrangement.

[shorty123]

Thanks GreenV8s i will lokk tomorrow, much appreciated, i do remember noticing an eronious wire with a spade terminal hanging loose, but for the life of me couldnt find anything to attach it to... the sender local to the plenum was connected, think i need to look harder!

Ta again