Function testing factory Gauges.

[oneluckypops]

I would start off with continuity testing.

It's my understanding most of the gauges run off resistance of the sending unit. So you would need to setup some type of adjustable resistor?

Having all the ohms of the gauges is fantastic, BUT to just function test the gauges and the board you can simply hook power and grounds to the appropriote terminals, then for the gauges them selfves just ground them, if the gauge pegs it is working. If your dead set on testing for the correct ohms then I would suggest to just pick up an old sending unit from the junk yard and test the ohms of it, like C4 said 0-90 ohms, connect your multimeter to it while your moving it so you know the exact ohms while you observe the gauge.

Okay so forgive me, it's been a long time since I was trained on a volt meter, and that was very basic training that hasn't been used in years.

If I wanted to test my temp sensor for ohms, how exactly would I need to connect it? Pin on sensor to battery positive or negative? Or something else?

If your just testing the ECT sensor then you would set your multimeter in the Ohms position, then touch 1 lead to the terminal on the sensor, the other lead would need to go to ground, OR if your bench testing it touch 1 lead to the terminal and the other lead to the body of the sensor

 

[sonicbluezx3]

If your just testing the ECT sensor then you would set your multimeter in the Ohms position, then touch 1 lead to the terminal on the sensor, the other lead would need to go to ground, OR if your bench testing it touch 1 lead to the terminal and the other lead to the body of the sensor

I did this and it didn't read any ohms. It's a brand new sensor.... and I actually checked two of them. Not sure why it wouldn't read anything....

 

[89Suburban]

Having all the ohms of the gauges is fantastic, BUT to just function test the gauges and the board you can simply hook power and grounds to the appropriate terminals, then for the gauges themselves just ground them, if the gauge pegs it is working.

I didn't realize that could be done without harming the gauges. So you are saying that can be done, full power direct to the gauge without any resistance and it will not damage them?

 

[oneluckypops]

I did this and it didn't read any ohms. It's a brand new sensor.... and I actually checked two of them. Not sure why it wouldn't read anything....

Are you sure of your settings on the multi meter? test it on something different and see if you get any readings

I didn't realize that could be done without harming the gauges. So you are saying that can be done, full power direct to the gauge without any resistance and it will not damage them?

The instrument cluster will have a pigtail with it, you will need to trace the circuit board out to find out which wires are Power wires and which ones are Ground wires, after you hook both the power and ground wires to the board just trace out the gauge signal wires back to the pigtail, then touch the sensor signal wires to ground and the gauge should peg. When you turn the signal wire loose from ground it should then drop to 0 again.

 

[sonicbluezx3]

Are you sure of your settings on the multi meter? test it on something different and see if you get any readings

When I touch the two leads together it beeps. It is set to beep when it finds resistance. It only has one setting for ohms as well, so I'm not sure how i could be doing anything wrong.

 

[Driver4r]

When I touch the two leads together it beeps. It is set to beep when it finds resistance. It only has one setting for ohms as well, so I'm not sure how i could be doing anything wrong.

I thought touching the lil prongs together was 0 resistance, cause it doesnt have to travel thrue anything.

 

[oneluckypops]

When I touch the two leads together it beeps. It is set to beep when it finds resistance. It only has one setting for ohms as well, so I'm not sure how i could be doing anything wrong.

i am curiouse to see what your meter looks like, post a picture of it. It sounds like your checking continuity and not ohms.

 

[HotRodPC]

Temp Guage NOT Working

I'm a bit stumped on my Temp guage. I bought a new sender and still don't work. The guage goes to about 140-150 degrees when I shut the key off and the Oil Pressure goes to about 30. Turn the Key to On, Both guages go to Zero. Start it, Temp never moves Oil instantly jumps to 40. Oil, Volt and Fuel gauges working fine. The clock even works fine. But I can't get the Temp to read. I did ground the Temp Gauge wire that goes to the sender with the truck running and it goes to infinite HOT like it's supposed to, so I know I got the right wire and everything that guage does tells me it's working right, with the infinite HOT and moving home to 140-150 without power. Any other ideas?

 

[RetroC10Sport]

Sender?

 

[HotRodPC]

Sender?

Replaced it with a Brand new BWD WT359P one form Adavanced Auto yesterday. Said to be for Guage, and said to be Exact Fit for 85 K1500. I'm thinking of trying someting though. I did use Teflon tape to seal it. I wonder if Tef Tape would keep it from grounding to the head? So I'm thinking of trying to Vise Clamp a wire to the Sender, and then clamp the other end to ground and see it that will make the gauge read. Not the terminal of course, just the housing itself. If it's not grounded, the gauge can't read the thermistor right???

 

[HotRodPC]

I just noticed the Box Says WT359Z, but I Look it up, it's still compatible. Not sure the difference, but it should work fine.

 

[89Suburban]

Replaced it with a Brand new BWD WT359P one form Adavanced Auto yesterday. Said to be for Guage, and said to be Exact Fit for 85 K1500. I'm thinking of trying someting though. I did use Teflon tape to seal it. I wonder if Tef Tape would keep it from grounding to the head? So I'm thinking of trying to Vise Clamp a wire to the Sender, and then clamp the other end to ground and see it that will make the gauge read. Not the terminal of course, just the housing itself. If it's not grounded, the gauge can't read the thermistor right???

I always wondered that too about the sealing stuff on the threads, especially for the temp sensor for the TBI trucks.

 

[RetroC10Sport]

Replaced it with a Brand new BWD WT359P one form Adavanced Auto yesterday. Said to be for Guage, and said to be Exact Fit for 85 K1500. I'm thinking of trying someting though. I did use Teflon tape to seal it. I wonder if Tef Tape would keep it from grounding to the head? So I'm thinking of trying to Vise Clamp a wire to the Sender, and then clamp the other end to ground and see it that will make the gauge read. Not the terminal of course, just the housing itself. If it's not grounded, the gauge can't read the thermistor right???

I think you're on to something there.

 

[oneluckypops]

Replaced it with a Brand new BWD WT359P one form Adavanced Auto yesterday. Said to be for Guage, and said to be Exact Fit for 85 K1500. I'm thinking of trying someting though. I did use Teflon tape to seal it. I wonder if Tef Tape would keep it from grounding to the head? So I'm thinking of trying to Vise Clamp a wire to the Sender, and then clamp the other end to ground and see it that will make the gauge read. Not the terminal of course, just the housing itself. If it's not grounded, the gauge can't read the thermistor right???

You have a DVOM? Just do a voltage drop test.

Set your volt meter to DC volts, Touch negative lead to Battery negative POST, then touch your Positive lead to the case of the sending unit. Observe voltage reading. Anything more the .03 - .05 volts is excessive.
Another way to test for voltage drop is to:
1. measure the battery voltage at the battery POSTS. Record your readings
2. Connect negative lead of the multimeter to the case of the sending unit.
3. Connect positive lead to Battery Positive POST. Record your readings.
You shouldnt see anymore then a .03 volt difference from testing direct to the battery versus the sending unit case.

IF you see more then a .03 difference then touch the negative lead to the engine block, should be within .02 volts of battery voltage.


Your questions brings up a question for me though. There seems to be alot of electrical questions and problems from time to time. I have been thinking about doing a techincal write up on Proper procedures for testing electrical systems.
Would this be something that anyone would get any use out of or would I be wasting my time?

 

[RetroC10Sport]

I'd say it would be a good write-up.