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Emergency braking event
Friday traveling on NC Hwy 52 just prior to the I 74 interchange.
I was on cruise control at 60 miles per hour. I was coming around a blind curve and and instantly saw a full two lanes of vehicles stopped in the road. I immediately initiated a extreme braking action and stopped about 100 feet short of the stopped vehicles with another vehicle on my left.
I recovered my composure as I said loudly to my wife OH S!!! as I saw the stopped vehicles.
I then notice having to hold brake pressure tp keep bus from moving forward as we were no on an incline.
I then noticed RPM at 1500, I tapped the accelerator and RPM climbed but returned tom 1500. I reached down and lifted the pedal and it made no difference. I had put transmission in Neutral and applied parking brake.
I turned off the ignition and then turn on ignition and it restarted at 1500 RPM.
I turned of ignition and restarted and this time it returned to normal RPM.
The traffic was beginning to move and i pushed the drive button and there was no response. I then saw a do not shift light on dash and the 6 in the transmission display was flashing.
I pushed the d button numerous time to no avail, and now traffic is bypassing me on the shoulder and left lane.
I turned of the ignition several time and on third try the blinking 6 in display became solid and when I pushed th D button the transmission engaged.
I continued to my destination and return today with no further abnormalities.
Any thoughts would be appreciated. I remember some previous post about having to move a bus to unlock the transmission if I remember correctly.
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8 Replies
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Ck. the ground, be sure transmission module
, is grounded to the body.
as far as RPM is concerned that’s could be a
throttle positioning sensor. Hope this helps.
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For some reason, your transmission went into “limp home” mode. There are a few reasons why that would happen, but likely causes are wiring harness between the TCU (Trans Control Unit) and the transmission, Input speed sensor, output shaft sensor, etc. Probably best to take it past a Detroit Diesel shop and let them look at the logs, etc.
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Just took our Coach into Florida Detroit Allison in Fort Myers, FL this morning. They ran the codes (and, printed out for my records).
Fortunately, I was able to clear the Check Transmission dash light, get the Coach out of limp mode/1st gear and back into 6th; and, have the speedometer work again – to drive the 54 miles from Naples.
The end result was replacing the transmission Output solenoid and adding a new pigtail connector to the Speed sensor. No more Check Transmission warning light or, a D-2511 Code: Transmission Output Shaft Sensor.
While it was there…had them grease all the drive shaft Zerk fittings, too.
Coach is operating wonderfully now – and, we have the confidence to begin our @4,500 mile journey back to Indio, CA (via Wisconsin and Danville, MO).
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Glad you got it handled but I would hope the 3 driveshaft zerk fittings are lubed regularly.
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They will be…going forward! 🙂
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Do not forget the fitting where the belt tensioner arm pivots under the fan clutch.
With no lube the bushings wear and the gearbox to clutch belt starts getting eaten up by side to side movement.
Prevost calls for lube every 6200 miles.
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Will do!
Thank you, Jon.1999 XLV X-6872, liberty #440 -
That one’s a bugger to get to but necessary.
Chuck
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