Temperature gauge stopped working, points down

[bruscreen]

My temperature gauge recently stopped working. I'm not sure what they normally do when powered off, as mine has been inconsistent for the past week before it quit.

I noticed one day when the car was off, that the gauge read over 200 degrees. Turned the car on and it dropped to about 100, so I just told myself it's an electric gauge and that's it's home position.

A day or two later I shut the car off and noticed the gauge pointing straight up. As before, once I turned the car on it gave me just the readings I would expect.

The next day I was driving home and glanced at the gauge to find it pointing straight down. I got my multimeter out and got 10 V between the sensor and the block. I reached behind the gauge and tried tapping to see if it was just stuck, but still nothing happens.

Does this mean it's time for a new gauge? I'm planning a trip with the car in a couple of weeks and although I've never had temperature control issues, I don't like not being able to tell what's going on.

[DMC5180]

Does this mean it's time for a new gauge? I'm planning a trip with the car in a couple of weeks and although I've never had temperature control issues, I don't like not being able to tell what's going on.

Not likely. I went through this Spring, I ended up removing the Instrument cluster and cleaned ALL of the copper contacts on the flexible PCB. This also fixed a few poor contact issues with the back lighting bulbs.

Needle at 12:00 means you have lost the reference signal (open circuit) from the temp sender. Needle at 6:00 you lost ground or +12V to the gauge itself. Or the temp sensor wire is shorted to ground.

Just clean everything and you should be good to go. Also verify the trace contacts with an DVM (Ohms) you should get something less the 0.06 Ohms on every test to ensure solid contact. Also Scuff the Wavey Washers and Nuts on the gauge stud posts. All this stuff is 30+ years old know. Tarnish and Oxidization is starting to show up more and more often.

[WelmoedJ]

Not likely. I went through this Spring, I ended up removing the Instrument cluster and cleaned ALL of the copper contacts on the flexible PCB. This also fixed a few poor contact issues with the back lighting bulbs.

Needle at 12:00 means you have lost the reference signal (open circuit) from the temp sender. Needle at 6:00 you lost ground or +12V to the gauge itself. Or the temp sensor wire is shorted to ground.

Just clean everything and you should be good to go. Also verify the trace contacts with an DVM (Ohms) you should get something less the 0.06 Ohms on every test to ensure solid contact. Also Scuff the Wavey Washers and Nuts on the gauge stud posts. All this stuff is 30+ years old know. Tarnish and Oxidization is starting to show up more and more often.

My gauge did that a couple of times (at 6).
Waited until the engine reach operational temperature.
Then hit the side of the binnacle firmly but not too strong.
Needle went up to normal position.

After some of those "failures" the gauge never has been disfunctional again.
Try this before disassembling the car (binnacle).

[Elvis]

I'm with Welmoed,

tap on the binnacle with your flat hand and it should jump back.



I also sometimes have the needle pointing upwards (10...11 o'clock) when shutting
the car off while pushing he brake pedal.

[Bitsyncmaster]

I'm with Welmoed,

tap on the binnacle with your flat hand and it should jump back.



I also sometimes have the needle pointing upwards (10...11 o'clock) when shutting
the car off while pushing he brake pedal.

If that fixes it then your pretty sure the bad connection is in the binnacle. Another thing to try is unplug and plug back in the bulkhead connectors.

[SS Spoiler]

I keep a bent paper clip to nudge the needle through the odometer hole.

[Elvis]

If that fixes it then your pretty sure the bad connection is in the binnacle. Another thing to try is unplug and plug back in the bulkhead connectors.

Can you explain why this would be a bad connection in the binnacle ?

[DMC5180]

Can you explain why this would be a bad connection in the binnacle ?

I think he meant Within the Binnacle, as in the Instrument cluster housing PCB or Harness connection.

[bruscreen]

It would sure be a relief if I can get it back without disassembling the binnacle. I just got back from a car show with the Frazer (1980 and older, the D didn't qualify) and I think I have about enough time to warm the D up tonight.

[DMC5180]

Are you a Virgin binnacle remover?

[bruscreen]

I haven't pulled the binnacle yet. I have a dash to replace but I'm hoping to wait until winter, it's going to take me a while to get it done. I do need to get in there at some point, as I have a turn signal indicator bulb out.

I didn't have to warm the car up. I just started it and tapped a couple of times. From the left side pushing right, nothing happened, but reaching behind the signal/horn lever and tapping the bottom of the binnacle upward directly below the temp gauge did the trick. The needle came off the 6 position and went to 100 degrees.

I drove around a bit, and shut down a couple of times. Along the way, I noticed that "normally" the gauge returns to the 12 position when the key is off, flips to the 6 position when the key is turned on, then goes to the proper reading. Once, it stuck at 6 again, and again the tap fixed it. Can't help wondering how long that will last. Are the contacts accessible from under the dash at all?

[DMC5180]

Are the contacts accessible from under the dash at all?

NOPE.

I have pulled the binnacle enough now that I can literally do it blindfolded in 3 Minutes. Its really not bad at all. If you have digital camera lay it the floor and snap a photo looking straight up.

You will see a Paper air duct and plastic molded duct W/on metal strap bracket holding it up (2 screws) Remove the ducts. Now you should see (4) M4 nuts (7MM socket If I recall) (w/large washers) protruding from the Fiberglass shelf. Access to one of them is partially obstructed by the Turn Signal Flasher Cube (remove it) for access. With the 4 nuts removed the binnacle is now loose. It is still attached by the Speedo cable and 2 wire harness connections. Raise the binnacle up so you can get your hand under and behind the cluster to remove the connections. The Speedo cable retention is a metal spring tab. Push towards the housing to free the cable housing. The electrical connectors have Internal TABs on both ends. You squeeze them inward to release the connections. Thats IT. The whole binnacle w/cluster will come out of the car.

Then you will see the back side of he gauge package with all the gauge retainer nuts and bulb holders. It's pretty straight forward from there. 6 or 8 screws hold the instrument housing in the binnacle. CAUTION be VERY CAREFUL NOT to Lean the the cluster housing face down on a flat surface. (the trip reset shaft is fragile and will break) ask me how I know. Set the cluster face down straddling 2 stable objects so it allows room for the shaft protrusion.

[mluder]

I'm having similar problems and have been using the "spank the binnacle" method but I wouldn't recommend it. My binnacle is in kinda rough shape already and the love taps aren't making it any better - the foam is soft and you're likely to damage or crack the outer covering and have it start flaking off.

One thing I've noticed and I'm curious if others have seen it... When I turn off my car the temp gauge needle does one of 3 things - jumps to 12:00 (sometimes drifts there slowly), stays where it's at, or drops to 6:00. When I start my car the needle more often than not jumps violently and gets stuck in the 6:00 position. Typically I turn my key to the ACC position first to see where it's going to land before fully starting the car. If it buries the needle a couple of off and an to position one will often resolve it. If not, it's spanky time.

I know that all my ground locations have not been cleaned as I should have done as soon as I got my car. I've done a couple - I do them when other projects get me near them. This being the case I'm sure it has a lot to do with my symptoms. I intend, like the original poster, to replace my dash mat and re-dye my interior pieces this winter. I've been sitting on the parts since I got the car waiting for new binnacles to come out so I could do it all at once... But, you know where we are on that one. I'll probably use that as an excuse to do some major work behind he dash, center console, and binacle.

One other tip I've picked up on this board... Make sure all your electrical accessories are turned off before shutting off the car. As previously mentioned, it can cause a voltage spike which sends the needle all over the place.

Cheers
Steven

[bruscreen]

I pulled the binnacle out Saturday in hopes just disconnecting and reconnecting the wires at the back of the circuit board might help. It didn't help much. The gauge is only a little more likely to work the first time, or the first tap. Biggest change has been I don't see it running backwards anymore (so far, knock on wood...). Before I took it apart, sometimes the needle would get stuck closer to the 5:00 position, and then it would go up the right hand side of the gauge. Took some fiddling with the key to get that back on track.

I ordered some LED bulbs to go in there the next time I take it apart.

[WelmoedJ]

I pulled the binnacle out Saturday in hopes just disconnecting and reconnecting the wires at the back of the circuit board might help. It didn't help much. The gauge is only a little more likely to work the first time, or the first tap. Biggest change has been I don't see it running backwards anymore (so far, knock on wood...). Before I took it apart, sometimes the needle would get stuck closer to the 5:00 position, and then it would go up the right hand side of the gauge. Took some fiddling with the key to get that back on track.

I ordered some LED bulbs to go in there the next time I take it apart.

Since you have it out, use some wires to connect it to 12V and ground.
You will need another wire to simulate temperature.
Use the electrical diagram to ensure the correct connections.

I had the unit out once and could not find what was causing the bad behavior.
The axle may have been "greased" in the instruments factory, but not sure as I couldn't detect greasy stuff.
Cleaning probably is hard to do as this is delicate equipment.
Look and judge what's wise.

[DeLorean03]

Pull the white bulkhead connector located directly under the yellow bulkhead connector. I have a friend this week that was having some of your symptoms - turned out to be a bad connection at the white bulkhead connector. Remember, the one underneath the yellow connector (I stress this because there are 3 white ones).


The bulkhead connectors are under the "black box coil cover" - located in the back right wall, passenger side - of the engine bay.