Hey act, I got some bad news.

So I was getting voltage earlier and didn't realize I had my multi-meter plugged into the 10V section. I was wondering why it kept sparking up when I touched the terminals on the half circle connections. I watched the lights flicker afew times on the dash before they cut out. Now none of my dash lights work anymore. My brights light still comes on as well as the night lights inside.

The worst thing though is that I am getting no voltage on anything now. Not the voltage stabilizer, all of the terminals before that had readings are now showing zero. Did I fry my circuit board? How bad could this be?

Thanks.

 

It's hard to say whether you fried your circuit board or not. First thing to check is if you are getting power to the cluster. My Haynes manual diagrams really don't help me that much 'cause they show the '85 having power coming through the three pin connection on the back of the speedometer - which you don't have since yours is mechanical. The only examples I have laying around are the later models.

Try to find out where power from the ignition key gets to your cluster and measure voltage there. Make sure your multimeter is set to measure volts. If it is set to measure amps it can cause a short circuit (which sounds like what may have happened in your case). I you are getting voltage to the cluster then you may have fried the circuit board. Later model clusters have a small flexible plastic circuit board that acts as a fuse for the cluster. Don't know if earlier models have one or not.

 

Hey ACT I am going to start a new thread for this. I need to try and find the power source for the mechanical speedo. I have no turn signals or flashers now. I noticed during this process of taking my cluster out that my front signals went and now my back have gone. I really need to get this working I just believe this is all being effected by loss of power to the cluster. I also do not have the flexible circuit board. I see what you are talking about on my 92 cluster though.

So this is what I found.

I plugged in my 92 cluster in the 85 car and got the same results. Literally none of the idiot lights and no voltage on the regulator. SO it is definitely a power source issue. My fuses are all fine giving off well over 12 for each holder. My hazards do work I realized but my turn signals do not. I am assuming that is because of there being no power to the cluster. I would really like to find the power source. I believe I did not fry my board but its power source is just obsolete right now. Let me know what you think before I start a new thread.

Thanks

 

I would expect that behavior when plugging in your '92 cluster since power comes in the 4 pin edge connector on the speedometer on a '92. You don't have that connector so it won't power up when installed on your '85.

Over on brickboard there is a guy named Art Benstein that knows these clusters inside-out. He's also the owner of www.cleanflametrap.com. I'd start a thread on brickboard and he will help you out

 

Thanks.

 

Hey ACT here are some pics from my circuit board. Thought you may have wanted to see. I believe that black and burnt track near the half moon connector is the culprit. My alternator also went out tonight. I believe it is from the cluster having no power as well. IF I remember correctly that battery light in the dash helps keep the system charged. I thought I noticed my car starting weaker recently :P

Here is the link

https://imageshack.us/my/images

Any thoughts on a solution?

Thanks!

 

The battery light on the cluster needs to be working in order for the alternator to start charging the battery. I saw your thread on brickboard and indeed it sounds like you found your problem. Solder a wire to replace the burnt trace as Art recommended and then reinstall the cluster to verify the functioning of the batt light. If it comes on when the key is turned to the II position and goes off when you start the car then you should be ok.

Have you been driving with the cluster not installed?

 

Yes ACT I have been driving without the cluster installed for the last few weeks. So I do believe it was a matter of time.

Since the burn trace is wrapped around one of the pin areas, could I just bridge the area by soldering right onto the solder spot from an earlier non-burned trace? I was a little confused because its not an actual area of the foil trace but burned around a solder joint. Could the new bridge still be affected?

ART said my link didn't work. Try this one. https://postimg.org/gallery/2ceoo63gq/

Thanks

 

Now that I can see the images I don't see any evidence of burned traces. I checked out Art's replies on brickboard and it looks like he's got you on the right path to diagnosis. Basically similar tests as I was recommending. Just jumpering the pin instead of using a resistor

 

Could you give a quick guide on jumpering the pin?

I have never done this before.

Thanks

 

Disconnect the sending unit connector in the trunk first. Then plug in all the connectors on the back of the cluster but leave the cluster resting on the steering column. You need a piece of wire with one end connected to ground. Turn the key to the II position and verify that you have power to the cluster. Then touch the other end of the wire to pin 1 of the half circle connector. You should be able to do this by back probing where the gray wore enters the connector. You should see the gauge go to full. Be careful so as not to touch any other pins when probing. If the gauge moves then repeat the procedure by touching the gray wire to ground in the trunk. If the gauge goes to full then the problem is with the sending unit. If the gauge doesn't move when grounding the gray wire in the trunk then the problem is a break in the gray wire that runs from the cluster to the trunk.

This is same procedure that I described for the resistor but using a wire instead. It's also what Art was describing

If you have problems back probing the connector you can solder a straight pin to the end of the wire to make a small probe

 

ACT,

Thanks for the information. Last question,

When I ground the pin will I touch the pin on the black wire? Is that the ground I attach to and then touch the gray wire?

Thanks

 

Any point of bare metal on the car can be used as a ground. I don't know to which black wire you are referring - it may be a ground or it may not. Black on a wire does not always guarantee that it is a ground. I always look for a bolt that is screwed into the body and is not painted for a ground point. Affix one end of your wire to that point leaving the other end free to back probe the connector. In the trunk you can see the brown wire runs to a screw that just attaches to the metal body that acts as a ground for the fuel sending unit. If you remove the center console kick panel just to the right of the gas pedal you will see a similar ground point that screws into the transmission tunnel and has one or two wires attached. You could use that one.