Cadillac Repair: 1987 cadillac eldorado digital dash problem, cadillac eldorado, radiator cap

Question
i recently been having problems with my digital dash in my eldorado it will fade in and on and turn off for days at a time and then stay on for a while i have checked all of the fuses and they are fine the car is in great shape and i have no idea what it could be and i would like to know if is something that i could adress or whether i have to take it to a mechanic. i also have another question about how hot this car should run it has a 4.1 v8 in it and it only has 67k miles on it and i have had a new radiator,water pump and thermostat put in, in the last 6 months since i bought it. the digital read out says that it runs about 190-212 degrees and has gone as high as 225 but it usually runs at 197 is this to hot and if so how hot should it run?

thank you very much for you time
ian  

Answer
Hi Ian, I'll answer the temperature question first. With your car the temps you are seeing are considered normal. When it gets up around 220 degrees both fans should be on. But if on a normal day like 70-90 degrees out and the temps started getting into the 230's then that would be cause for concern. Also with the hi ambiant tempuratures we are haveing lately along with running the a/c I wouldn't be surprised to have the gauge read into the 220's. One thing that would help is if they didn't change the radiator cap with the radiator I would suggest replaceing it after the car has sat for 4 hours or overnight. The reason being is that if the cap isn't able to hold enough pressure that will lower the boiling point of the coolant mix and lead to running hotter.

    As for the digital dash. If it is just the speedometer head that is acting up then there is a good chance that it is going bad and will need to get replaced. You could have yours sent in for repair by a dealer but it would probably be cheaper to get one from a junkyard/auto recycler. Depending on how long you feel you will be keeping the Eldo would be the decideing factor. There is a module that sends power to the digital displays and if the climate control panel was haveing fadeing out problems along with the speedometer then replaceing the central power supply might get the display working again all the time. It is located above the accellerator pedal and is a silver box aprox. 5" by 5" and 1" thick. If the last 3 numbers in the part number end in 406 you have the updated module and it may or may not be the cause. If it ends in 396 that was the part that the bulletin said was more prown to act up and need to get replaced so replaceing it would be a good idea. There are checks useing a voltmeter on the specific wires that would need to be done to verify that the correct voltage is being sent out of the module and you would need a manual for that or subscribe to AllData.com and useing your computor you would then have access to all the information needed to diagnos and fix this problem.

    Hope that helps and let me know if you need anymore help. Bill