Looking at buying an 87 GTA - car is a Canadian car (km's), but when the car starts up the digital dash show MPH, and the Odometer (whole message board) is not showing any info. Current owner (friend) is saying after you drive it for approx. 1 hr, it will switch to KM's, and the odometer will work as it should. I have seen this happen when driving the car with him. Any hints on why this may be occuring? thx Mark

 

I had a similar problem, what my problem was is one of the chips on the IC that has gone bad. When the IP warms up somthing on the chip makes contact. It also may be something on one of the circuit boards that has a bad connection...

On one of my cars the Dash would blink in and out, although it did not effect the Odometer, when I finally got the IP partially out I isolated the chip that had the bad connection, since GM does not typically use standard part numbers on their boards & chips it virtually impossible to actually replace the rogue parts by crossreferenceing, unless your an electronics whiz. you basically will have two options: Replace the IP, or take it to someone that works on GM electronics and get a quote... I ended up buying another IP.

There may be someone here that can help you more, but thats my experience.

John

 

Sometimes going over every solder joint a second or third time will improve one or more connections. Usually what happens is that the original solder joint has excess flux that never got 'burned away' properly when the solder was applied or the joint was improperly soldered to begin with leaving a 'cold solder joint'. If you 're-flow' the solder joint with the proper heat for the proper amount of time it will generally clear up the integrity of the solder joint and you will have no further problems.

Sometimes you can carefully look over each of the solder joints with a magnifying glass and good lighting and 'suspect' a number of solder joints that can be 're-flowed' first. If one of those happened to be the bad joint you will have saved quite a bit of time not having to visit every solder joint on the board.

If there are plug-in chips it might help to remove and re-insert them 3 to 5 times in an effort to 'clean' both sides of the contact. Sometimes oxidation is bad enough that the socket needs to be replaced.

Do not overlook harness connectors. Both sides of any one contact need to be clean.