Erratic Gauge Readings

[Gil_J]

I have a 99 Country Coach, 98 Prevost XL, and begun to get erratic gauge readingstoday. The 24 volts would go down to 20Vfor a while and bounce around before returning to normal and doing the sameagain. The front and rear air pressuregauges would read normal and occasionally bounce to zero for a few secondsbefore returning to normal.

I checked the 24V at the battery jumper connections and thevoltage was as expected at just above 27V. So, I’m confident the problem is most likely a poor connection in thecommunications bus to the gauges. BTW, Ihave a Country Coach with a glass display. I doubt it’s the computer that drives the display given all other gaugesperform normally.

Any thoughts on which connectors to start with? Any thoughts on my logic being flawed? I’m in Minot, ND so getting commercial helpis not going to happen here. They have a Detroit Diesel shop, but it doesn’t doservice; they only sell parts.

Thanks,
Gil

[Pete]

The first thing I would suspect would be an intermittent ground, especially if the gauges drop at the same time. I am not that familiar with the CC systems, and am sure one of the CC owners will chime in with a solution. It is just a thought. Hope you get it figured out quickly.

[JIM KELLER]

Gil, Assuming you have already done a dash reset I would check the ribbon connector in the computer cabinet. If you don't find the connector behind the locked door remove the top of the ledge behind the drivers seat. It is held on by velcro so it just lifts up. I believe there is a diagnostic procedure if the odometer and hours window turns a different color when the erratic readings occur. This specific issue tends to go in the direction of the computer. All other issues are usually a ground or connection problem.

[Gil_J]

Jim,

Actually I didn't try a reset given the computer did come up. I thought the reset was really Windows boot reset. I did remove and replace the ribobbon cable and every other cable I could find. I'm still trying to find where the 24V is monitored for the voltage display. You don't happen to have the wiring diagrams for the computer and related sensors do you? Is there a procedure for using the reset or is it just a push when ready operation?

Thanks,

[JIM KELLER]

Nothing special about the reset. Just open the guard flap and push. I think you are correct, it is just a re-boot for the computer. I will look for more information.

[JIM KELLER]

Gil, According to my schematic wire # 30 ppl is for the Main Air Tank and # 31 brn is the Aux Air Tank. Wire # 391 ppl is the 24 volt constant v+ from the chassis batteries to ECC for chassis battery monitor, and to GSD circuit board in the overhead cabinet.

[Gil_J]

Jim, great information. What is the GSD board and where is it? I know the air pressure device that changes from air pressure to an electrical signal is in the steering box door.

[JIM KELLER]

Gil, I called Country Coach to find the location of this board for you. And this is where it starts to not make sense. GSD stands for Generator Shut Down Board. It is supposed to be in the cabinet above the drivers seat. Armed with this information I don't understand how this board could play a part in your false readings. Then again I am continually surprised by what I learn about our Bus. As you probably know Country Coach is back in business and some of the old employees that were there when they built our Buses are back to work. If you call them you need patience because they are not overstaffed. Greg in Technical Support is a good contact. If he does not know the answer he will find out by talking to the right person and call you back. 541 234 2167. Also, take a look at them on the Internet.

How is your trip going ? Will you be in the area of Country Coach ? Might be able to get a lot of questions answered. Wish I could make it a destination someday.

[Gil_J]

Thanks Jim! I sent CC an email and they are trying to run down what drawings they may have. I have several wiring diagrams, but nothing on the communications links to the computer!

Thanks again for reaching out to CC. BTW, do you know how to test the automatic generator start to see if it really works? On the system I had before from Magnum Energy, there was a test button as well as a display to let you know it was actually monitoring the voltage. The best I can tell the system we have is based on "trust us" it will work when needed.

[dale farley]

Gil, You may want to check with Miles C. if you don't receive quick help from CC. Jim may know if Miles has these particular drawings. Miles is the best I know at troubleshooting schematics. I haven't heard of anone having this problem.