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Cadillac Repair/1988 cadillac sedan deville - fuel pump relay


I am trying to locate the fuel pump relay on my 1988 Cadillac DeVille.  I have the owners manual, but the diagram doesn't seem to match up.  Have tried to search for info on the internet and get several different answers.  Fuel pump is not working and need to determine if it is just the relay before replacing the fuel pumb.  A mechanic friend said may follow schematics of a 1989 because a number on the driver's door includes "688" which he said indicates auto is a mid-year 88, so could actually be an 89.


The 1988 body is completely different from the 1989-1993 body style. The 1988 body style was all by itself and was longer than the min 1985-1987 models. If you look at the owner's manual for fuse box locations, you should find the relay in the fuse box(s).

I have yet to find where a relay fails on a regular basis. That was always the supposed answer when raditor fans quit--never a relay issue. Power antenna-never a relay issue and on and on.

The best thing to do is use a test light on the power wire running into the fuel pump under the car with the key on. No power, then you need to work your way to the source and who knows? It might be a relay. If you have power going to the fuel pump, you need to drop the tank and replace the fuel pump, which it probably is.

Let me know what you find.  

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Rob Painter


Alarm system questions cannot be answered on this forum. These systems are not what I can answer. Without being physically at the vehicle and not knowing what kind of electrical service has been done on the vehicle, there is no possible way to give an accurate answer over the internet. My expertise is in Ignition/key based anti-theft systems. These issues include GM VATS (resistor chip in key blade) PASSLOCK (MRD)-ignition lock rotation based, no special ignition key and the PKIII Transponder (computer chip in key) systems. These systems are not alarm based and are integral with the starting of the engine. This is why I cannot diagnose alarm problems without physically looking at the vehicle: Alarm systems are a completely different annimal than ignition key/lock based anti-theft system. Many alarm questions come from vehicles 10 years old, and since older, many hands that had been involved over the years.I am an expert in all GM factory (ignition/key based)systems. Alarm system questions pose to many situations beyond my knowledge as to what has been done to the vehicle over the years. Some guy may have actually wired the stereo into the alarm system. Who knows? Over my past 30 years in vehicle wiring repair, I have seen unbelievable wiring disaters done by guys that consider themselves "mechanics." I have seen stereos and alarms intalled using surgical tape. I have seen modules burn up, un-fused circuits, wiring jambed between the doors and even lamp cord used for a starter kill. To answer alarm questions over the internet without examining the vehicle is like asking; What does it take to remove a dent?


Education/Credentials-ASE certified. 11 years with a GM dealer and 17 years with a repair facility dealing with only the repair of theft recovered vehicles.

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