WillyXJ

I've been trying to install a cruise control setup in my 98 XJ and have a bit of a problem that my searching has not provided any answers to. After installing the servo, plugging in the electric and vacuum connectors, installing the clockspring, and installing the switches, I can only turn the green dash light on and off (yes, I have used the AB and AC switches).

I have not tested for any vacuum leaks because the servo is not getting any power. From the wiring diagrams in the FSM, the servo gets it's power from the brake lamp switch which is connected to the PCM. When I test pins 3 and 4 on the brake lamp switch, I'm not getting any voltage reading. I have tested the brake lamp switch for continuity which checks out fine. I have tested the clockspring and am getting good continuity through it and the different voltages based on which cruise buttons I press.

I'm at a loss as to what the issue could be and fear the problem lies with the PCM. Have you any good suggestions as to where to go from here? Could it be that some 98s actually support the AD switches?

CCKen

"Could it be that some 98s actually support the AD switches?"


I would think there is a chance the 99+ AD switches could be used. I suppose it would depend upon when your '98 was built, the factory may have started using some '99 stuff in your '98 if it was built at the end of the production cycle.. If your '98 PCM was flashed to use AD switches it may be your issue (?)


'98, like '97, are sort of odd ducks in that they were transition types.

vulcan1701

I have a 96 so your problem may not anything to do with my solutions.


Two things.
1) Sometimes my green light wont come on when I hit the CC switch
2) My green light comes on but it wont let me set the CC.


My solution to both is to tap the brake. If that doesn't work then I put the trans into neutral and back into drive.
Either one of these always fixes the problem. I am just too lazy to mess with a permanent fix.

WillyXJ

Bringing this back for an update.

When I called the dealership, they informed me I'd need the AC switches. Check. I ended up putting this project on the shelf as I was at a loss. While working on another project, I had the connector to the vacuum canister unplugged. When I went to reconnect it, I gave it a wipe and the Nintendo blow. Today I gave it a try on my way home. Press On/Off, see green light come on, press Set while doing about 37mph, feel gas pedal pull away from my foot. That was exciting!

After a short bit, traffic slowed so I cancelled the cruise. Then I tried setting it around 30mph, but nothing happened. Since I don't have an owner's manual, I assumed the minimum speed for cruise was 35mph. I ended up pressing On/Off and the light went out. A bit later I was back up doing 35mph so I thought I'd try the cruise again. The light never turned on. In fact, I couldn't get it on until I pulled into the driveway.

Now I'm confused again. Any thoughts as to what the problem could be at this point?

WillyXJ

Well, I keep using the cruise control every chance I get now and it seems all problems have gone away. I'm just going to chalk up my original problems to a dirty connection. Thanks all for trying to help me.

moparado

On my 2000, the CC system from day 1 won't let me 'set' below 40 mph or a little less. Once in a great while i can set it around 35+ mph.
Maybe it was designed that way for safety reasons, don't know.

Otherwise it works fine when set ~40+ mph albeit with some hunting until it stabilizes in about 10 seconds.

A note on the CC enable indication light.
I live out in the boonies so my CC is enabled a lot which means the light bulb is on a lot. Must of changed out that light bulb a half dozen times over the 17 years i owned my XJ.
Finally had enough and installed a LED bulb. Problem solved.