rustypigeon

I have a '94 22re and the coolant gauge now stops at 1/4 instead of 1/2 up on the temp scale like it used to when fully warmed up. The thermostat and sending unit has been replaced since then with the same results.

To test the gauge, the FSM directs you to put a 3.4W test light on the wire connector to the sending unit and connect it to ground. A good test shows an illuminated test bulb and a coolant gauge that moves toward hot when the ignition is on.

When I put my 3W test light into the connector my gauge goes to 1/2, and the test bulb blinks at a steady pace, about 2 times per second.

I am wondering if this blinking is normal. The FSM states that the light should illuminate, it does not mention blinking. The gauge gets power from the integration relay and I am wondering if I have an issue with that. The blinking is very steady, as if a circuit board is controlling it.

If anyone has a test light and 10 minutes of time, I was wondering if you could tell me the results of your test. Page BE-36 of the FSM show you how to test it. I am curious if anyone else gets a blinking test light. Thanks in advance!

http://personal.utulsa.edu/~nathan-b.../6combinat.pdf

^here is the link to the FSM, page BE-36 shows the procedure

Edit: I should have added that all other gauges show normal indications, and the "gauge" fuse shows a steady voltage.

rustypigeon

Update: I backprobed the Integration Relay and found a steady voltage. The source of the blinking must be coming from the instrument panel.

I still don't know if the blinking test light is normal however.

rustypigeon

Anyone?

scope103

I tried mine today (during a gasket job). I got a STEADY light.

The input to the fuel gauge IS interrupted; it's a 60's vintage switching power supply to provide a steady voltage. Otherwise, the fuel level would display differently with engine running (because of the higher bus voltage).

Could your temp gauge work the same way? We're both the 1994 vintage. And having the temp display be the same engine running or not is not so important.

rustypigeon

Thank you!

I didn't want to put any time into diagnosing something that might have been normal. Your report of a steady light seems to indicate an issue with mine.

Looking at the wiring diagram, it seems the only connection between my fuel gauge and temp gauge is the ground. The speedometer also shares this ground and my speedometer is functioning normally.

I will have to poke around tomorrow and see if I can find anything wrong. I will also try the test with the engine running and see if the frequency of the pulsing changes.

Thanks again for your assistance!

scope103

What you want to see is if the frequency changes with bus voltage. Since an alternator will hold up the voltage even at idle, you just need to compare running and not running.

Of course, if you're doing that, you might want to look at the oil pressure sender too. I'm told that the sender itself "pulses," with the pulse frequency changing with engine rpm (what you care about is the duty cycle, which would indicate oil pressure, but that's more difficult to measure). I tried to test that, but gave up after a short while (the connector is hard to jumper).

rustypigeon

I got a chance to check out the test light with the engine running. Blinking is much the same as with the engine off. I did discover that the light is steady for the first 7 seconds or so after the ignition is turned on. I didn't do any other checks but here is a video...