2nd Gen Non-Engine/Transmission Cruise w/ injectors

[AggieJustin]

Has anyone found a way to "desensitive" the cruise control on an '01 6-speed with injectors? Since it's all electronic, restricting the vacuum won't work.



If I have it set around 70-75, it's not so bad on hills. It will up the boost then hang there, and right as you break over the top it will fluctuate some. But most times on hills I take over manually with my foot to help the mileage out some. The part where I have the problem is when I first engage the cruise. As soon as you hit Set, it throws down a burst of acceleration then falls back to the set speed. Haven't found a way around this one yet.



So I know we've got some electrical geniuses out there, was hoping that maybe someone has worked something up for this.

 

[OTRPU]

Had big problems with cruise control on my 99 auto. When I set the speed at around 65 it would take off like a shot. 85 or so it would stabilize then gradually decline to the set point. Thought it was in the steering wheel switches, had them cleaned first with contact cleaner. Some improvement, not much. Talked with other owners in truck stops. They said replace the cruise control thingy on the firewall. Called Reliance Truck & Auto from Sterling, CO on my way through Colorado going to West Coast. Had them order the part, made appointment for install the next day. Also, had ordered new steering wheel switches two months earlier, they were on National Backorder. Well the firewall thingy did the trick. I understand that the now slight increase in speed from the set point when first set is the turbo has to spool up. I can minimize this effect if I throttle just alittle past where I want to set the speed then set the switch as the truck is coasting down to the set point. On the road I had to get this working better, pain in the but to use the throttle 10 hours a day. Was afraid I'd get a speeding ticket when resetting cruise when slowing for all the construction slowdowns. Set for 40 and the thing would race back up to 70. Just knew I'd be explaining to some cop that it was my cruise control doing it on it's own. Can hear him now, well fella, step on the brake then.



Cheers, Steve J.

 

[TowPro]

The fix was posted by somebody else on here. There is a vacuum line that goes to the cruse servo near/under the battery on the drivers side (I think).



Look at the size of the vacuum line, go to a tropical fish store, and buy this brass valve they sell that has a knob on it that allows you to the flow. Put this in your vacuum line, and turn down te flow until the cruse works right.



I never tried it, but it sounds like it would work, and others posted it fixed there problem!



My 98 was real bad with this, then they put a flash into the pcm I think, and it got better, but still was really bad.



My 02 is better, but still is worse then any other car/truck cruse I have driven.

 

[IdaH.O.Train]

I don't recall experiencing the problem you're describing, Justin. When I set my cruise there usually isn't any noticeable difference in the way it's running. If I inadvertently let off the accelerator before engaging the cruise, then it will accelerate.

 

[Extreme1]

The cruise on my '94 might be different but there was a write up in the TDR a few years back about this too. The cruise needs to be "retrained".



On mine, you set the cruise, let it find where it's going to run, the hit the "off" switch. I usually wait a few seconds in case there is some energy storage there then turn it back on, set it and let if reach a steady speed. Repeat 20-25 times. It works every time and it usually needs to be done after the batteries have been disconnected.

 

[AggieJustin]

Well, when I set the cruise I don't have near the speed increase that OTRPU described. Mine is only an increase of 4-5 mph before dropping back. But it's enough to spool up the turbo before dropping back to set speed. I've tried speeding up slightly when setting it, but it still beats me to the punch. If I hit set while I'm coasting, it's even more noticeable as it has to spool the turbo even more.



I noticed it a little before the DD2's, it would slightly overshoot the target speed (~1 mph). But now with the injectors, it's even more touchy.



TowPro, the vacuum trick works on a truck with an auto transmission. But the manual transmission with the diesel engine does has a fully electronic cruise control system. No servo. That's why I was hoping there was an electronic solution similar to the vacuum solution, to slow it's response times.

 

[JJW_ND]

New truck have electronic cruise!

Somewhere in the 2001 model year the cruise system was switched from a manual vacunm system (94 - early 2001) to a full electronic (ECM controls speed). Those with the older vacunm pump should first make sure the cruise servo is working fine. Any time the cruise tends to greatly accelarate right after setting would benifit from a new cruise servo (about $50).



I Have a very touchy trottle (darn extra power) and since replacing the servo the cruise is rock solid and very gentle. I did also add a piece of 12 guage wire (3/4" plastic jacket with the copper wire pulled out) inside the vacunm line that comes from the servo where it connects to the firewall.



Not sure what can be done on a Electronic cruise other then software update or reflash.





jjw

ND

 

[Mundgyver]

AggieJustin,



Are you sure your truck is electronic for the cruise. If it is then I beleive it sets the speed by the rpm of the engine in the ECM.



I think you are looking for my fix to the problem. Your truck should be equipped with the vacuum system. You will find the line to the module on the drivers side going under the battery box. Trace this line up to the fire wall for your connection point. What you want to do is find a precision adjustable needle valve. The price can range from $10 all the way up to about $60 for a SS one. You want one that you can lock in place once the desired setting is completed.



Splice the needle valve into the vacuum line to the module up near the fire wall where you can get at it for adjustments. Close the valve all the was down snug (not tight) then back it off 1/2 turn and lock it down. Go drive the truck and see how it feels. If you still get a surge, close the valve by 1/2 the amount you opened it up or 1/4 turn. What will happen is a slowing of the vacuum draw from the module. The module will not respond as fast as before.



The effect will be that you will notice that it take longer for your cruise to engage. Also you will notice that you might have to drop back a couple of miles per hour before you feel the throttle pull away from your foot. Thats OK and is normal. The end result will be that the tighter you make the needle valve the slower the response.



Now for every day driving or even towing the effect will be like you have your foot on the throttle as the slowness of the response will seem more natural. My truck has 275's and a EZ-Comp box.



It does not surge and with the exhaust brake turned on during cruise mode, I can hold my speed to with in 1/2 mph. I have had this set up since about 10,000 and am now at 95,000 with no problems. If you have any questions give me a call or drop me an e-mail .



-- email address removed -- or call (503) 201-6569



-Wally- Alias (Mundgyver)

 

[AggieJustin]

Thanks Wally.



After reading the service manual, it looked like the cruise was completely electronic on my truck. But since you also have a 01 w/ 6-speed, I'll have to take a look at it this weekend when I get back to my truck.



I'll let you know how it works.