Econocruise

My first post: I am working on a diesel powered, rear wheel drive motorhome equipted with an "Econocruise" cruise control. Customer said that the cruise quits working and so does the speedometer. A roadtest confirmed that the cruise drops off but I never saw the speedo quit, but then again it was not a long roadtest. I have replaced the speed sensor on the tranny and the cruise still drops off. I have never heard of this system so can anybody help me with a wiring diagram and/or troubleshooting help? This system will work fine for about 5 miles then it will loose about 3-4 mph for a minute or so then return to the set speed. The resume function seems to work fine but the accel does not. Thanks for your time. J.K. 

Hi Woody,  I don't have a wiring diagram, but with a little more info, I may be able to help.  Does this cruise control have an electronic or vacuum type servo? Does the speedometer work by a cable or electronic signal? Where is the cruise control getting it's speed signal? If the speedometer works by a cable, is there a signal generator inline near the transmission for the cruise control?

the12volt

This system has an electronic type servo with four wires. The speedometer works electronicaly(magnetic sensor on output shaft). I would think that the cruise gets its speed signal off of the same sensor. This motorhome is similar to a bus chassis and the engine is located aft of the rear axle with a short drive shaft and I don't see any other way that the speed signal for the cruise could be generated. It is difficult to see where the wires are tapped because there are wire looms bundled together throughout this chassis. One thing that I did notice on the road test is that the throttle is harder to press when it is pushed greater than 50%. I don't know for sure if this is normal for a diesel engine.

Woody

Hi Woody, check the throttle connection from the servo. Make sure the cable is taught with no slack, but not causing the engine to idle higher than normal. If you find that it's difficult to pull the throttle where the servo is connected, see if you can change the angle to make it easier or even incorporate a throttle adapter to accomplish the same.

BTW, since you changed the speed sensor, has the speedometer quit working at all? If so, the lead(s) from the speed sensor may be shorting out somewhere and may need to be replaced. One thing you may want to try if the speed signal is still an issue, is adding a pick up coil and magnets on the drive shaft to generate a speed signal just for the cruise control.

If time is becoming an issue, it may be quicker and more cost effective to replace the entire cruise control. Rostra ( https://www.rostra.com ) manufactures a universal electronic cruise that should work on that vehicle, but if you still have a speed signal issue, it will have to be fixed before any cruise will operate properly. You may also want to contact them to ask if they are familiar with the Econocruise, it's possible they even make it.

the12volt 

Thanks for the tip.

Woody.

This could be UK Econocruise.

Electric Actuator had 4 wires. RED / White, RED / Blue, Yellow/White and Yellow/Black. Usual to fit with its own spped pickup, about 2 inches square and 1/2 inch thick with three core cable, brown - ground, blue - ignition and GREEN / WHITE - signal.

Hoewever, they did have trouble in UK with damp penetrating actuator. I have a service letter somewhere about it.