Hello, folks!

I'm a newer member in this great forum. After posting my introduction in the "Intro" subforum I'd like to ask a little question about the dash cluster pinout.

The last week my dash cluster dead... I didn't know what happened, but it became crazy and started to show rare signs in the displays. Then I unmounted it and I checked all pinout looking for the incident reason. The cluster has 2 connectors, one 24 pins connector where the cluster received the information selection required by the driver from the central control panel and another one which has 32 pins, where all the sensors and the ECM and cruise control are connected.

I have some doubts about 2 pins (I include some links with the connectors and wiring diagrams below):
1) From the smallest connector (24 pins) the pin numbered as B1 seems to be a ground for a central control panel, but when I disconnect the connector from the dash this pin doesn't be a ground. Does the cluster supply the ground for the central control panel when I connect them?
2) From the biggest connector (32 pins) the pins numbered D8 and D9 should to be the vent/vacuum valves control for the cruise control, but I have tested these pins and there has 0 ohms to ground for either pins, so they seem to be connected to ground... is this normal? I have disconnected the cruise control actuator until I'm sure that there isn't any failure because when I buy another dash I want to preserve its health.

Here we can see some diagrams:

http://www.batee.com/corvette/dcrg/w...tor_pinout.htm
http://www.batee.com/corvette/dcrg/w...ng_diagram.htm

Thank you very much!!!!

 

#1 = all the stuff in the DIC loops back to the cluster unless you have a manual transmission DIC where there is an extra wire present.

#2 = unless you know exactly what is/does do not ohm test solid state equipment you have the potential to destroy it.

The pin outs are pretty much the same for 84-89. Typically a grounding issue will drop the displays out and turn both turn signal indicators "on" at the same time...if the cluster still has voltage applied to it. Flickering or dead panels could be a number of things within the cluster from connectors to a bad power supply.

The year of the cluster and a better description of "it became crazy and started to show rare signs in the displays" may help the diagnosis process.

 

Thanks for your response!

Ups! I hope to haven't destroyed anything doing the ohm test. I did this test with some lines (MPG serial input from the ECM, Speed Signal output to the ECM, sensors inputs and the cruise lines...). I did it with a multi-tester, which send a little voltage and minumum amperage... anyway I won't repeat this test anymore :bb

Yes... I forgot to do a description of this :o My Vette is a 1986 model with ABS, VATS and electronic climate control. I show you a picture of my crazy cluster:


Cheers!

 

First guess is this looks like a low voltage condition to me. Low voltage will do strange things to these clusters.

Is there any flickering going on with the LCD panels or do they appear steady with the segments they show?

Is the car's battery output voltage 12v or higher when the random LCD segmentation condition occurs?

Was the DIC switch panel connector connected during the time when you took the photo in your post?

When you first turn the ignition key to "run" does the cluster do the normal self test in which it should appear to light up all the LCD segments at once for a second or two or does it just look like the photo all the time?

 

I doubt you hurt you cluster with your ohmeter. This warning is there because old ohmeters used to use 22 volt batteries for the high resistance range and 22 volts can damage solid state circuits. Modern ohmeters don't use this high a voltage any longer, but some use 9 volts and those can do damage. Fluke ohmeters have a switch position for testing diodes and is safe for testing solid state circuits. You can use another voltmeter and measure the voltage across your ohmeter probes to see how much voltage is there.

 

Click here

 

Hello! all the LCD panels are steady since the car gives voltage to them. I have tested the voltage and there is 12V. The cluster never does the LCD test... since a voltage is received it shows the same appearance.

The DIC switch panel was connected when I took that photo, but I connected the cluster to an external power out the car and it had the same behavior. I think that its processor or its memory is broken

Cheers!

Yes... I have read this, but the LCDs aren't flickering... they are steady all the time

Yes... I have tested my multitester with another multitester to see what the voltage test gives, and it shows only 3 volts... I think it isn't very dangerous for a state solid circuit, but I won't repeat the test to preserve the electronic circuit's health

When the cluster failure appeared I was driving the car on the road and I saw the cluster doing rare things, showing so much strange figures. Then I stopped imediately the car, switched off the ignition and then switched on again, but the cluster never recovered itself.

Another thing that I can see is that the switches from the control central panel gives 5V for each signal when I select them... is this normal? 5 volts is the correct voltage for the input switch signals from the central control panel? I thought it's possible because they seems to be a TTL signal value (5V for a "true signal" and 0V for a "logic false" signal), but I'm not sure of this

Thanks to all!!!

 

You might find this useful, it from the 86 FSM. Good Luck !!
http://members.shaw.ca/agent86/Instr...%20Cluster.pdf

 

Thank you very much! I'll read this useful and I'll check everything it says

 

Thank you! My cluster failure isn't that some LCD segments are on... the problem is that the cluster doesn't work... it doesn't show the speed neither tachometer values, ... it is dead

Thanks for your post

 

I suspect that the failure was caused because of the cruise control actuator. When I measured the resistance values for each wire which goes from the cluster to the cruise control actuator I was surprised when I measured 0 ohms on the D8 and D9 outputs (these pins are vent/vacuum valves control outputs) to ground. I think that 0 0hms of resistance between these wires and ground are very dangerous if the cluster gives voltage to there because they seem to be grounded.

I don't know if these lines must to be grounded, but I have unplugged the cruise control actuator until I'm sure about what these lines do.

If anybody knows these outputs and their normal values I'll be very happy to receive all data of them

Thank you so much!

 

I found it!!! : http://members.shaw.ca/dankai/Cruise%20Control.pdf

I measured the resistances as this document says and they are ok, so I don't know why the custer had broken.

I only need to know what is the voltage output for the signals which go from the central control panel to the cluster. Does anybody know if 5V is the normal value for these signals?

Thanks!

 

Well lemme ask this. Did you resolder everything like Batee.com said?

If you shine a flashlight into the LCD can you see your Tack and Speedo working....with the absence of a backlight?

 

Hello! I didn't resolder anything because I was looking the electronic boards and they seem to be good. My cluster lights because somebody did a new circuit for it... I think it was broken in the past and it has a redundant lighting circuit.

I don't know where I could to start to solder... there are a lot of integrated circuits

Cheers!

 

The main places to start soldering are the larger components, i.e. capacitors. Especially everything on the power supply board. Next would be to clean and reheat the pins that connect the two main pc boards. These weren't very well built units, and expecting the solder joints on the larger components to last unsecured in a rather hostile environment the way they are mounted is ridiculous.

 

Thank you! Today I'll resolder these pins. Yesterday I unmounted all boards and I was looking for a bad connection, but I can't see anything wrong.

Cheers!

 

Be sure to clean the rubber pieces and the places on the pc boards where they make contact with rubbing alcohol right before you reassemble it.

 

Hello! Finally I'll have to replace de dash because I probed to plug it to a external 12V power and I felt that the microprocessor was burning (I put my finger over it and the circuit was very very very hot), so I think that the main reason for this malfunction is that the microprocessor is completely broken The worst thing is that I don't know what the reason which caused this problem was. I hope it has broken becuase of its age and not because of a bad signal from the car.

I have won a bid for a cluster in Ebay... I hope to not break it too.

Before I plug a new cluster, if anybody knows how much voltage goes from the central control panel to the cluster for the selected measure inputs (instant fuel, average, trip odometer, ...), please, tell me I measured only 5V... is this correct?

Thanks!

 

Igualito que en España eh?

¨The same in Spain, isn´t it?¨ IRONIC MODE ON, obviously

 

Some spanish people should learn a lot!!! This forum is 500 better than any spanish one