Tester
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What do the connectors look like? I canāt tell from the image in the link Tester provided. Are they circuit board edge connectors with fingers that look like this?
These are gold plated but yours may be tin plated.
If so, as George pointed out, a pencil eraser makes a very good burnishing tool. It will not damage the finger contacts and will remove oxidation. Itās only one side of the connection but often the more problematic one. Worth a try. Otherwise maybe you can post a picture of the connector ends so we can see how best to clean themā¦
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They work in a similar way your home computer connects to your printer. The printer has its own computer, and it ātalksā to the desktop computer using a method both have agreed to use. In the case of a desktop computer/printer, itās called LAN protocol. In a carās case itās called CAN protocol. Mechanics generally use a Scan Tool to query and command the other car computers. The Scan Tool is itself a portable computer, and it knows the proper CAN protocol to ātalkā with the carās computers. Not all Scan Tools are alike. Generally the least expensive may only be able to communicate with the powertrain computer (PCM), and only have a subset of the functions available. Mechanics use a pro-level scan tool which is able to communicate with more of the carās computers, and with more complete functionality. For example an inexpensive scan tool may not be able to communicate with the body control computer (BCM) or the anti-lock-brake computer (ABS) , but a pro-scan tool could. With modern cars, even if you want to do the repair yourself as a diyer, sometimes it makes more sense to hire a shop (which has the pro-scan-tool) for the diagnosis, then you can do the repair yourself if you like.
https://www.techopedia.com/your-car-your-computer-ecus-and-the-controller-area-network/2/32218
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I wonder what was used on this ā87 for communication.
Looking at @Tester ās link, these displays sound like they āfade to blackā at some point and canāt be fixed.
Update 3
Been going through the service history receipts, an found this ādash-cluster sent for electrical repairs, sadly the odometer reading couldnāt not be repaired, since there are no shops in Norway that we know of that has the correct scan-tool.ā But this was from over 10 years ago.
I also found out that the fuel gauge sort of works, since it was reading correctly when i was driving on a steep incline, but went back to āfullā when i drove on flat roads. The same thing happens with the oil gauge, although that doesnāt gradually change, but jumps between reading correctly and not. I want to check the fuel tank and engine for these sensors or cables, any idea where to look?
There is also a slight issue with the gas pedal, its kind of sticky, like pushing it through syrup, the first half inch, and then it works fine. As you can imagine, that makes it a bit hard to do smooth acceleration in the lower gears.
I donāt know if it is connected, but when i let off the gas pedal, the engine jumps a bit. Like the throttle is closing a bit roughly or something.
Iāll probably end up sending the dashboard pcb in to a repairshop either way.
As far as the fuel gauge faulty erratic operation, the problem could very well be the sending unit inside the tank . . . which IS still available
As far as the oil pressure gauge, since you have the digital dash, you apparently have the 3-terminal engine oil pressure switch, which is also available. I would lean towards simply replacing it and inspecting the wires while youāre at it
Iāll state my opinion again . . . even without a wiring diagram for the digital instrument cluster, Iām of the opinion you could get get it going, or at least improve its operation, by going over and resoldering every single solder joint, testing and replacing every single resistor, diode, transistor, etc. as necessary. Iām guessing pretty much everything except the actual readouts and maybe power supplies are parts which are available, if you know where to look and have much patience.
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The best solution for the oil and fuel display might be to bypass the broken module entirely, install an aftermarket gauge system. Owning an 87 American car in Norway will likely require you to invent solutions. As far as the sticking gas pedal, that may just require a little lube in the right place. Check for free operation all the way from the pedal to the throttle valve. Separate the sections if possible then test each section independent of the others. The engine-jumping sensation on deceleration could be the same problem, or it might be related to the higher than normal intake manifold vacuum that occurs then. Engine oil might be getting sucked into the cylinders via the valve guide seals for example. Ask a helper to drive behind you. Do they notice any dark smoke out of your tailpipe coincident with deceleration?