rufrob

When I got the car last year all the gauge worked. Gradually the temperature gauge started occasionally flickering or reading higher than normal. Now it doesn't work at all no jump when the key is turned to accessories. The cluster was cleaned and checked out fine. Power applied to the gauge and A connection makes the gauge move but once connected it doesn't move.
So there is a problem in the wiring. I cleaned all the grounds and don't see any cuts or damage to the wiring.
Any idea where to check?

931guru

http://www.clarks-garage.com/shop-manual/elect-19.htm

rufrob

Been the CG and did several searches. I've looked at the wiring diagram too. Just wondering if anyone here has dealt with the same or similar issue.

tempest411

Have you considered the obvious-a bad sending unit? You can connect an Ohm meter in place if your gauge connection and see what the resistance is from cold through warm up. The wiring can be loop checked to insure there isn't a short to ground on the sending unit lead, that your ground path at the gauge is good, and you can test for +12V at the gauge as well.

rufrob

I've changed the sensor 3 times.
I'll try running a new wire between the harness junction and the sensor and the cluster.

Jfrahm

Hmm, do you think that would have been helpful info in your first post in this thread?

rufrob

Sorry. Thought I did. To recap. When I bought the car last year the gauge worked but began to flicker and read inaccurately so I changed both sensors with used ones from spare engine.

The car was still not running right so I bought 2 new after market sensors which caused a hard starting when cold and same flickering on the temperature gauge and intermittent working.

Then I bought new OEM sensors which solved the hard starting when cold but the temperature gauge stopped flickering and stopped working completely.
The voltage was reading lower than the actual alternator output and the oil pressure pegged with the ignition on. A shop checked and cleaned all the connections so now the voltage and oil pressure read accurately and rise with the ignition on.
Only the temperature gauge doesn't rise and doesn't work. But it worked on the test bench.

tempest411

Odds are then there's something up with the wiring. A simple loop check with a meter should help confirm that. When you do this, flex the harness around across as much of it's length as you can ('wiggle' test). This will hopefully allow you to narrow down where any break is hiding, so you can carefully get into the harness and repair it.

orig944

Assuming this is the '86 951 in your profile, pull the wires from the sending unit and ground the Blue with Yellow stripe wire. This should cause the gauge to go to maximum hot. If it does not, then the gauge is bad or there is an open circuit. The wire passes through the central electric box on terminals F11 and E41. I have no idea where these are since I have an early car, but it would be a good place to look for a loose connection.

rufrob

Thanks. Actually it's an 89-944 NA.

rufrob

I just realized I don't know where F11 and E41 terminals are. Google was not helpful.
Please tell me where to look.

orig944

Schematic says F12 and E42 for your year. These connections are somewhere on the bottom of your relay and fuse module, also called the central electric box. My car doesn't have this but perhaps someone with experience with late cars will chime in.