91-92 Cruise Control Servo Rebuild (Pictures Soon)

[Tactical Bacon]

This write-up is applicable to the 91-92 MJ and 91-96 XJ with a 4.0 engine. It may also be applicable to Renix era cruise control servos and vehicles equipped with other engines. 

Tools Required:
10mm socket

3/16" socket

Two small flat blade screw drivers or miniature pry bars

Needle nose pliers

Channel locks

 

Begin by using your 10mm socket to remove the nuts securing the servo to the bracket. Once they're off, there may be two retainer washers holding the studs in the bracket. Use a screwdriver or needle nose to pry them away. Remove them from the studs and you can take the servo out of the bracket. Removal of the battery is not required. The cone at the end of the actuator cable can be slid down and the hairpin that retains the cable to the servo pulled out. 

Once you have it on the bench, use the channel locks to slowly work your way around, prying the lip of the bucket outwards. Don't put pressure on the plastic, just grab the lip of the metal bucket with the teeth of your pliers and bend it outwards until the plastic half separates from it. You can then inspect the diaphragm for any tears or punctures. Then you can move to disassembling the electrical portion of it if need be.

 

There should be 3 small holes in the underside of the plastic half. Spray a little Liquid Wrench or a similar lubricant in each hole to lubricate the o-rings inside each tube. Next, use your 3/16" socket to remove the screws holding the electrical connector cover in place. Once you slide it off, use a small screwdriver under the left and right sides of the metal plate under the circuit board to pry the actuator assembly out of the plastic. Once it's high enough, you can just grab it and pull it out. You can test for continuity between where the copper winding wires are soldered to the board for each solenoid. I had a resistance of about 1200 ohms. There's also a diode on the board so set your Multimeter to Diode Mode.

 

Once you finish, reinstall the actuators into the plastic, wiggling it back and forth to get them lined up in their holes. A little silicone grease on the o-rings helps them like any other o-ring. Put the diaphragm back in the bucket and line up the spring on its backside with the ring on the plastic half and then press them together, making sure the lip on the diaphragm lines up with the groove in the plastic half. These don't appear to have been assembled with any adhesives but I used a little bit of contact adhesive to hold the diaphragm to the bucket and the plastic.

 

You can use some electrical tape wrapped around the servo to hold it together then slowly work your way around the lip again, using your pliers to roll the bucket back over the plastic half of the servo. Then reinstall your servo back in the Jeep in reverse of removal.

Congratulations, you've rebuilt your cruise control servo.