Bus can only idle

[ToyMan]

Started to go on a small trip this morning and the CEL was blinking. Codes produced were 12,13,16,43, and 46.

Coolant level is nice and green in the viewer window. I jumped the coolant sensor and still get the same codes.

Is it possible that the code 46 is triggering the other codes?

Any help would be greatly appreciated.

While waiting for replies, I am going to check the chassis batteries to see if I have a dead one. Especially the one that drives the ECM.

TIA

Ron

[ToyMan]

Checked te batteries. All is good there. Cleaned all the terminals.

Once the problem is fixed, does the ECM have to be reset to clear all the codes?

[rfoster]

Sounds like the same symptons a faulty Throttle Position Sensor produces. Engine only idles.

[garyde]

Hi ron. If it was a coolant, oil, fan, transmission sensor it would have shut down your engine. It is more likely your gas pedal sensor or your relay for high and low idle .

[ToyMan]

I did have the "retarder" CB tripped when I first looked atthebreakers.

The fast idle works.

[lonesome george]

Ron you might take a look at a thread in engines, transmissions, axles and wheels called witch hunt 10-11-2009 it has some good information on this type of problem.
I find the tripped retarder CB troubling.
If you go for a new Throttle Position Sensor purchase if from Prevost, about $100 and a new harness comes with it.
Good luck!

[ToyMan]

Thanks to all who replied.

The CEL codes produced were "inactive" codes so nothing in there was a show stopper. However, the "throttle position sensor" appeared to be the problem. I took the old one out and ran an ohms test on it and it appeared to fluctuate as I simulated pressing the throttle. At 4:30 today I ordered the part online from Prevost.

While still looking into possibilities, I thought about any buttons, switches, etc., that I had changed since my last trip. My doorbell did not work so I flipped 2 toggle switches that were on the drivers side wall just behind the seat. Those switches did not correct my dead doorbell (that's another story altogether). When I did the flipping, I did not flip them back. There are other switches in the area that control mobile and land connected telephones so I figured these switches controlled things related to that. So, while the engine was running, I flipped the one nearest the front and the blinking DDEC codes quit flashing. AHAH! I flipped the other switch and, I know most of you know, the throttle worked as usual.

I assume the first switch probably jumps connectors A to M thus displaying the inactive codes. The other one completely disables the throttle but allows the motor to idle.

I immediately called Prevost at 4:40 to cancel the order and the parts person said that the computer showed that Prevost Jacksonville had pulled the part, packed it and validated that the order was complete and ready to ship. In 15 minutes????? The order was placed about 4:25 and the person told me that the Jacksonville closes at 4:30 and he didn't think he could get the order canceled. I will find out tomorrow.

Anyway, I am happy that it now runs properly and I did learn a lot about troubleshooting on my bus. Below is a picture of the mysterious switches located on the right side of the diagnostic connector.

[Jon Wehrenberg]

Ron, Why not open the top of that compartment (there is a roll pin holding the parking brake yellow cap in place) and see what those switches might be connected to. Perhaps they have something to do with the DDEC reader next to them. It is hard to comprehend why a switch that would put you at idle would be where it could be knocked off just by putting something behind the driver's seat but that looks like what is happening. Somebody may have installed a remote reader (like a silverleaf) at one time and the switches were intended for that, but the installer did not realize they also had a secondary affect.

I hate owner installed "upgrades" without documentation. And that looks like what they are. At least consider putting a safety shield over them so they don't get switched accidentally.

[truk4u]

Those switches are Liberty installed, I have the same ones. Mine are clearly labeled ATEC test and DDEC test in the up position and the down position (normal) is "off."

[Kevin Erion]

Is that test to make sure the owner knows what they are for? Maybe a sobriaty test!

[Jon Wehrenberg]

OK, now I have it in context. In my 87 coach I had the plug for the reader and selector switch located in the steer compartment. Now I understand that they were just moved. So if I understand it right when the switches are in a certain position they take away the ability to run the engine above an idle. I wonder if that was intentional or if it was an oversight? They definitely need a safety shield over them so they cannot be accidently switched.

[ToyMan]

Jon,

They definitely need a shield over them. The driver intercom phone is installed in such a place that it is knocked off all the time. Even when I reach back to let the arm rest down.

Mine had no labels on them at all.

Thanks to everyone for the input and advice.

Ron