Great instructions, thanks.

 

So my cruise control still works, but since I fixed it I noticed that when I set the cruise control I lose about 5-10 mph before it actually engages and then it stays at that lower speed?

also, when I go up hills it doesn’t seem to adjust the throttle enough to keep me at my set speed. So if I’m set to 75 mph and I go up a hill my speed will often fall to 70 mph or lower?

anyone have any ideas?

 

On D1's I always do the D2 HELLA CC ECU swap. Much more reliable vs the old unit. The CC on the RRC/D1/D2 aren't like modern day vehicles with an electronic throttle body, and with that being said you really shouldn't even use CC when in hilly terrain. You have the slack in the kick down cable to take into account, slack in the TB cable, and an engine that isn't the most powerful in the world. I've had 2-3 D1's with working CC and it's great on a long drive on flat terrain, but on hilly stuff = best leaving it off IMHO. I'm also pretty sure the manuals for the RRC/D1 used to mention not using CC in hilly/mountain terrain.

 

I think I do need to adjust my kick down cable, but what is this you are saying about the HELLA CC ECU swap? I did replace my D1 with a D2 cruise control ECU, but I’m not sure if you are saying there are two types for the D2?

 

Yes HELLA CC Unit from a D2/P38 = way to go vs stick with stock unit which wasn't made by HELLA.

 

The CC units are tuned to match their motors. So, if you got a CC unit for a 4.6L, it will not have as much gain as one for a 4.0. Then if the 4.6 CC is installed in a 4.0 truck, it will seem very sluggish because it won't move the throttle at the tuned rate to respond to an error in speed. Conversely, if a 4.0 CC unit is installed in a 4.6 truck, it will tend to surge and overshoot.

When I use CC, I compensate somewhat by giving a couple clicks up after hitting set, before I completely release the gas pedal. That helps it catch. On occasional hills (highway not mountains), I just accept that it's going to slow down and take a while to ramp back up to speed. Make sure the hook for the CC actuator is barely off the throttle closed position. Too much gap there will mean the actuator won't be able to pull as far.

Hope this helps.