Oldtee

I have the shop manual with all schematics. I am having trouble locating a few things and I need somebody who has taken these things apart to give me a hint or two.

Problem: 85 Instrument cluster, speedomenter circuit.

The schematic 97-219 shows the central electrical system with nice numbers like k23, R13, k22, R12.

When I look at the electrical box I see the plug A-V (or what ever) but these plugs only have 12 or so wires and I can see numbers on the plugs, but they don't seem to relate. How are these plugs read with schematic in hand?

Next question: The speedometer uses plug B. Which one is that? The L, R or C enter? Also which way do the numbers read. Note: these are the plugs that go into the cluster main board.

Last question, presuming I can find the correct pin outs and I use a fluke meter, what would I expect to see if a signal were present and the car was running?

Last-last question: Is there a service bulletin that covers this?

Alan

Each plug has 10 pins. The plug letter is the first part identifying the shell. the next part is either a 1 or a 2. 1 is the left side of the plug (5 pins) 2 is the right side of the plug (5 pins). The final part is the terminal# where 1 is at the bottom and 5 is at the top.

Alan

Oldtee

With one peek you can win the game. Thanks. Maybe with this I can figure something out.

Any hint on using the fluke on the impulse transmitter output? Or, which plug is plug B on the cluster?

JP Rodkey

You're better off with an analog meter to read the pulses. A dirty way to check for signal is through the cruise control because the speedo and cruise use the same source. If the cruise works, you have pulses.

Oldtee

I have cruise control. But good reminder. I can check continituity up to the plug at the cluster. Would tell me the same thing.

Another thing I didn't do was go over the connections with a soldering iron. Right now things are dead. I bought a used cluster and installed that. The left side of that cluster was dead, so I removed it and took my speedometer out and installed the new cluster speedometer. NoJoy. Dead as a doornail. Now I am evaluation options, again.

One more cluster swap and I'm gonna be an expert. Now I can get the cluster out and back in in about an hour. Not bad for a seven decade old goat!

Oldtee

Update.

The center plug is the "B" plug on the schematic. Continuity all checked out so I pulled the cluster AGAIN and removed the speedometer from my cluster and reinstalled it in the new (used) cluster. It worked and I now have speed, but during the install I found the lights to the shifter in the tach don't work. They worked on the first install. Will trouble shoot that today if the weather holds and the creek don't rise.

Oldtee

Update and question.

All done, road test good. Even the shift lights work now, but they did not work with the car on the lift. What happens when you lower a car on its haunches shift lights work when they didn't work while lifted? Global warming, maybe?