Temperature Gauge Problem

[JackD]

I've got a '95 Previa that's just had a replacement engine put in a couple of weeks ago. All seems fine and the temperature gauge was behaving as normal, sitting just below halfway. However in the last few days, the guage has started behaving oddly, sitting at zero (as in the position with the ignition off) then suddenly shooting up to its normal position, back down to zero or possibly a random 'cool' position, then back to normal. I've checked that there's plenty of water and no signs of leaks, airlocks etc. From the behaviour I suspect an electrical problem, either at the sender or the dial. The needle movement seems much to fast for it to be responding to a 'real' temperature change. When I get the chance I plan to take the dashboard off and make/remake all the electrical connections, and then clean up the contacts at the temperature sender.

Does this seem like an electrical problem to anyone else, and is there any other place I should be looking for poor or dirty contacts?

jack D

[TheBigUnit75]

I had the same set of issues with my 4Runner. now the gauge is dead. I replaced my sending unit and the gauge in the dash cluster, even replaced the whole dash cluster. have current at the sending unit but nothing inside the dash. after changing the cluster, now I have a check engine light that was not on before.

[propnut]

Sounds like either

1. A wire has come off or there is a loose connector at either the gauge end or the sender end, most likely the latter.

2. The sender is faulty.

3. The engine earth strap has come loose

4. The gauge is faulty (highly unlikely)