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Got a bit of work planned on the car tomorrow and if I get time I'll be trying to work out why my idiot lights are behaving badly.

This is a New Zealand new 164, 1990, with the 3.0 V6 12V. Speedo in km, temperature in C, oil pressure in bar, etc.

The red light next to the temperature gauge is basically always on (it occasionally goes out for a while and comes on again a bit later). Temperature gauge reads normal and has been verified with a separate temperature sensor. Someone has bridged the two wires in the top of the coolant expansion tank, but it makes no difference if I remove the bridge.

The oil pressure warning light comes on often (not as often as the temperature one). The oil pressure gauge comes up to a bit over 4 bars (half way) immediately after starting. At hot idle, it reads maybe 0.5 bar which increases back to over 4 bar when the engine speed increases. The red idiot light usually (but not always) stays on throughout all indicated pressures.

The fuel light sometimes comes on at half brightness when there is plenty of fuel in the tank. It always comes on correctly (at full brightness) when the fuel is low.

I have checked:
- electrical connections to both oil pressure sensors and the sensor in the top of the coolant expansion tank
- two grounds at false firewall, one above gearbox (where gearbox strap connects), two on air intake plenum, and three above pedals inside
 

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Coolant temp sensor for red light dot in temp gauge is located in thermostat housing and is sensor facing forward next to timing belt cover. smaller connector is red light one and larger wider connector is for gauge. Sender is no longer available new so if light bothers you disconnect smaller wire terminal and ground it to chassis and see if light goes out. I just ground it permanently.

As for oil pressure red light. Disconnect wire from switch under distributor cap area on front head and test by grounding wire to see if light comes one. Then test switch with wire on motor off light one then start engine and with oil pressire gauge showing pressure light should go out if not you need a new oil light switch.

As for fuel light dimly on do you have ethanol gas? sometimes it just is what it is and you just need to let it glow.
 

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Discussion Starter #3
Coolant temp sensor for red light dot in temp gauge is located in thermostat housing and is sensor facing forward next to timing belt cover. smaller connector is red light one and larger wider connector is for gauge. Sender is no longer available new so if light bothers you disconnect smaller wire terminal and ground it to chassis and see if light goes out. I just ground it permanently.

As for oil pressure red light. Disconnect wire from switch under distributor cap area on front head and test by grounding wire to see if light comes one. Then test switch with wire on motor off light one then start engine and with oil pressire gauge showing pressure light should go out if not you need a new oil light switch.
Will try these thanks.

As for fuel light dimly on do you have ethanol gas? sometimes it just is what it is and you just need to let it glow.
There is some ethanol available in NZ (E10) but I don't use it. I guess I can live with this one!
 
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