I have a 06 columbia that has been having tranny problems. I will be driving along (no perticular gear) and my gear display will start flashing F and gear # I am in. during that time it is stuck can't change in to manual either. I have to pull over shut truck down and reset most of the time, there are a few times where it will change gears but the truck jumps like was forced to do so. also when it is flashing F and the gear # the speedomter drops to 0, which is really weird. I have changed the wiring harness to the transmission, change the speed sensor, throttle control sensor, had a couple of wires replaced and the xy shifter, have been considering replacing it (xy shifter) again, cause I was told it might not have been good when it was put on, I'm just not wanting to spend another 1000 for it. Wondering if someone else has had the same problems and can share some light. I have had it in dozens of shops and they never can find a code, and it don't act up when they drive it and it got bad enough that I have parked it, but I need to get it back out on the road. Please help!!!!!!

Im no tech... But to me sounds like the Clutch is gone....

we replaced the clutch just prior to this starting, but I figured if it was the clutch it wouldn't never work, and not just show its ass on occasions, but I'm no tech either

Grounds, grounds, grounds!

Take 'em all apart, clean 'em up and put 'em back. all the way back to the batteries.

Carefully disassemble and closely inspect all electrical connections.

Use the anti-corrosion spray of your choice into all connections that will migrate up the wires.

WD40 doesn't cut it. Termin8tor or one of the Krown products.

Any wire showings any signs of corrosion, any dings in the insulating cover, replace it.
The electrical signals for controlling these marvels require clean, clear wire paths.

Thanks Freightshaker we will try that.


Babyzodi

Hi There,

I am new here and this is my first post. I own a gearbox and differential company in South Africa and may be able to offer some advise on the problems you are experiencing.

I have come across this problem before and can point you in the right direction. The flashing "F" without the usual presence of a fault code is related to a current or previous speed sensor failure.

What usually happens is the sensor will crack and eventually break, normally logging a fault code 58.

The magnet in the sensor comes out and lodges between two raised sections of the tone wheel. A new sensor is fitted to rectify the fault and the magnet does not get removed off the tone wheel. This now affects the new sensors ability to give an accurate reading as it is affected by the magnet on the tone wheel.

Attached images show what i am talking about. The magnet is pretty small, but it can pick up a 1" spanner.

Another possibility could be a loose gearbox yoke nut. If the yoke nut is loose, this will allow the tone wheel to spin, as it will no longer be clamped between the output bearing and the yoke. A loose tone wheel will also give incorrect readings for the sensor.

Get the guys to check for those and let me know what they find.

Hope this helps.[ATTACH=CONFIG]1170[/ATTACH][ATTACH=CONFIG]1171[/ATTACH][ATTACH=CONFIG]1172[/ATTACH]

Hey,I'm new here and I am having the exact same problem, did you ever find out what it was?

Had the same problem with 2007 Freightliner,speedometer would go wacky intermittingly and sometimes check engine light would come on and truck would lose power and be put into some kind of safetry mode. After changing speedo sensor and tightening nut on transmission yoke the problem remained. Finally FleetPride sent me to a drivetrain specialist and they said that there was too much play between my transmission yoke and the bearing inside the transmission. This would cause my tone wheel to spin freely causing the speedometer to go wacky which in turn would cause the truck to buck and run awful because it was goverened at 68mph and when the tone wheel would keep spinning the truck thought that I was reaching the max speed and would cut off fuel etc. They had to cut off the yoke as it was frozen to the transmission shaft which was a bit risky because if they damaged the shaft I would need a new transmission. Actually I have 875,000 miles on the truck and they said that the transmissions usually go around 800,00 to 1 million miles so they recommended not to waste any money on the tranny. Anyhow they got the yoke off and replaced the yoke ,the toning wheel and a new nut and tightened it all back up. The play is now gone and the truck runs fine again but they still are not sure what caused it to loosen up in the first place so I will be watching it closely. May have dogged a bullet for now but a reman tranny was like $6,000 to $7,000 including a new clutch. Hopefully get a couple of more years out of this one but will be saving my money.

Thanks somemuch for the information i have freiliner columbia 2007 transmission smart shift. Im spend 5,000 all ready on the dealer on lynhurt nj they not fix i have F lettle on the dash. But i read you comen i see i have to chance the speed sensor i do. Now is off the lettle F..thanks for you comens

did you ever get fixed? Give me call would love to hear what the culprit was. 910 21two eight 1one three.