1987 GMC Jimmy Distributor cap and Rotor replacement

To replace the Distibutor cap and Rotor [they fit together as a unit when you get the two parts together]. First you need to mark with masking tape [or other such tape you can write on] the number of each spark plug wire and attach the tape firmly to each wire. DO NOT make any mistakes! Make sure you are numbering each wire with it's correct number based on the spark plug w/ wires position! Depending on if you have a 4,6 or 8 cylinder vehicle you will have 4,6, or 8 spark plug wires/spark plugs, and each has it's own number. You'll need to find out which is the number one plug ,number two plug, number three plug until you correctly number each one! You will end up with wires [either 4,6 or 8] going around the Distributor Cap. The one in the middle of the cap is the "COIL WIRE" leave this one unmarked cause you'll know that one stays in the middle. NOTICE- YOU need to positively find out which plug is which number with a VEHICLE MANUAL that shows you clear photos/diagrams of which plug/wire is which and i'ts position on the cap. Once you ID each wire then you need to mark your new DISTRIBUTOR CAP with the exact numbers in the exact place as the wire was.Now you can remove the wires off the old distributor cap and remove the cap and old ROTOR. Put the new ROTOR in. Place the CAP in the correct position as before and place the NEW Spark Plug Wires in there correct places based on the number you put on your New Distributor Cap.

A diagram may not be needed as its a reasonably easy fix to do on your own.the distributor ca p will only fit on properly one way because at the base of the cap locaters can only fit the distributor if they line up.When doing the spark plug leads do them one at a time and if nessecary write or mark leads as 1,2 etc .The rotor can only fit on one way but put a mark on the distributor to show where the rotor was pointing when you took it off and if it still points there when the new one is fitted.When changing distributor cap and leads they have to go to the correct place.Pays to mark the outside of distributor cap where the locating bits are On the new and old one.Fit the new cap and rotor then take a spark plug lead and fit to new cap 1 at a time.You can tell by lining up the marks on the outside of the distributor cap when you hold them one on top of the other.Good luck