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Renix Cruise Control Help

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I’ve been trying to add cruise control to my 89 MJ 4.0 5-speed with parts pulled from junkyard XJ’s. I believe I have everything and have tried a bit of troubleshooting but can’t get it to work. Any help or insight would be much appreciated. 


Here’s the install list:

• cruise control wire harness 

• cc harness plugged to “ACC” in fuse box on truck with inline 4 amp fuse unbroken

• speedo cable switched to two piece with speed sensor

• speed sensor plugged to cc harness

• brake switch swapped out for the one with extra terminals - plugged to cc harness

• brake sensor (aka vacuum dump valve) & bracket mounted and properly adjusted on brake pedal with the sensor plugged into connector from stock wiring harness and big vac line going to servo 

• servo mounted with cable connected to throttle body and connected to both cc harness plug and stock wiring harness plug

• yellow cc module plugged into cc harness 

• cruise equipped turn signal lever installed and plugged into cc harness

• football-shaped vacuum reservoir in place of the ball one with small vac line running to servo


Here’s all I’ve done in terms of troubleshooting:

• I have multiples of the module, speed sensor, servo, and harness and have tried various combinations excluding the harness because I know it needs a repair. 

• I have checked the resistance of the turn signal lever as instructed in the FSM and it seemed to all check out so I think no wires are broken in it. 

• Small vac line at servo sticks to my finger when pulled off servo so it has vacuum but I’m not certain it’s enough. Any recommendations on a vacuum measuring device?  All AC conrtrols work and reservoir seems to hold vacuum. 

• I have also plugged off the large vac line at the servo to eliminate the brake dump valve if it was the leaky culprit 


Also, if any one has a spare sensor and bracket for the clutch petal on a manual transmission I’d love to buy one. 



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14 hours ago, JPBraun said:

• cc harness plugged to “ACC” in fuse box on truck with inline 4 amp fuse unbroken

Using 88 Electrical Manual:

Single connector should be plugged to IGN (lower center of fuse box). Now I agree with you, if ACC is hot in RUN then it shouldn't matter, but it will not see hot in RUN/START (I1). The 4A inline fuse comes off the brake switch.

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