Temp gauge barely moves

1983 XJS HE temp gauge barely moves. I believe it to be a wiring issue. Any assistance greatly appreciated.


1983 XJS HE
1988 MERCEDES 560 sl
2007 SAAB 9-3 2.0t

do you mean it hardly moves from the cold position? If so, have you checked the thermistor and it’s wiring connection on the coolant rail on the A bank?

Have you tried replacing sender? Its quite cheap and easy, single wire going to it on A bank at front of coolant pipe (under air box)

Eric R. - try this test: 1) with the ignition turned off, unplug the harness single connector from the coolant sendor, located on the A bank; 2) place an end of a short wire in to the harness connector and place the other end of the short wire against a bolt on the engine, possibly temporarily securing it with a clamp - this will provide a direct ground path, battery negative ground, to the harness wire going to the instrument panel temperature gauge; 3) look at the temp gauge as you turn on the ignition switch ((do not start the engine)) for a few seconds, then turn off the ignition switch - if the sensor circuit for the gauge, and the gauge, are in good condition, you will see the gauge needle rise to the “hot” position and then return to the “off” position when the ignition is turned off; 4) if the circuit tests okay, then you will need to replace the sendor unit in the A bank - Tex Terry, II - 1991 XJS V12 Classic Coupe, 1986 XJS V12 Coupe - sent 7/30/2020 2214hrs. EDT USA.

Thank you. I will try out this weekend.


IMO i only see four possible causes:

Bad temp sender
Bad wiring between temp sender and gauge
Bad electrical connection on gauge
A side thermostat is stuck open (although it should eventually get close to N)

IMO, after testing, my 91 Jaguar barrel gauges are inaccurate. In short, I was not playing around trying to get the stock barrel gauges working accurately. I installed two Auto Meter temp gauges, one for each head with the sender’s installed via bungs welded into new ss water rails & oil pressure gauge . I mounted the three gauges in the clock/trip computer opening. This still left me with the barrel gauges to compare. Just a rough comparison : 210F on the AM’s reads bottom of the “N” on the temp barrel gauge. BTW, these reading are in Florida 90F traffic ac on high.

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I did the exact same thing, i LOVE knowing the exact temps of each bank.

I installed 180F thermostats, and as im driving and see those gauges pegged at 180F gives me immense comfort!

Just knock the plexi glass with your finger on hot (old Soviet method). There is a 90% chance that it will work as it’s happening sometimes with my gauge as well…