my truck is an 04, but I would check the grounds especially the one near the drivers side body mount and the braided one on the drivers side, in the back of the engine that hooks to the firewall , if yours is the same. My problem was similar but not to your problems extent,and cleaning the grounds solved the problem so far. the other thing is check your front wheel bearings to see if you have alot of play at 12 and 6 oclock. if a bearing is worn it could be affecting the speed sensor in the hub assembly. jsut my thoughts charlie

 

thanks for the advice

Charlie--thank you for the message. i'm putting it on the lift this weekend and will check for play in the wheel and also take a look at those grounds.

Thank you for the heads up..i'll post what i find.

 

need OHM rating for VSS 2006 Allison

Upon further diagnosing of the problem listed above I found no continuity from the wires entering the TCM back to the output speed sensor on the transfer case of my allison trans. Turned out to be a bad connector about 18" from the output speed sensor. i cut the connector out and made a hard connection. Result was a reading of 1.36 KOHM at TCM and 1.39 at the output speed sensor.

Reset codes, started engine and went for drive...still have the same problem. still says service brake system, still no speedometer and still get check engine light for no output speed sensor signal.

I looked on alldata, where i purchaed the info for my truck and they just give one resistance rating for "speed sensors". This truck has 3 of them. An input, a turbine and an output speed sensor. The alldata says they should be 2.4kohms. The input and turbine read 2.4, but the output reads 1.36... The problem i have is that i just purchased this speed sensor. So i am wondering if someone can confirm the resistance should infact be 2.4 ????

any help is appreciated.

thank you

 

Upon further diagnosing of the problem listed above I found no continuity from the wires entering the TCM back to the output speed sensor on the transfer case of my allison trans. Turned out to be a bad connector about 18" from the output speed sensor. i cut the connector out and made a hard connection. Result was a reading of 1.36 KOHM at TCM and 1.39 at the output speed sensor.

Reset codes, started engine and went for drive...still have the same problem. still says service brake system, still no speedometer and still get check engine light for no output speed sensor signal.

I looked on alldata, where i purchaed the info for my truck and they just give one resistance rating for "speed sensors". This truck has 3 of them. An input, a turbine and an output speed sensor. The alldata says they should be 2.4kohms. The input and turbine read 2.4, but the output reads 1.36... The problem i have is that i just purchased this speed sensor. So i am wondering if someone can confirm the resistance should infact be 2.4 ????

any help is appreciated.

thank you

I'm thinking toasted Xfer case, like this poor person (and one of mine, too).
http://www.dieselplace.com/forum/showthread.php?t=304560&highlight=transfer

 

still looking

thanks for the link. It would have been nice if he had written back to say what theproblem ended up being for him.

I think I already checked my fluid level, but after reading all that, i will again. I dont have any speedometer which i wouldnt think would be the case if the fluid was low.

i did some looking and found that the 1.36 resistance on the output speed sensor is within range...slightly low, but close enough from what i can tell.

I am now wondering if the TCM needs to be reprogramed or the pc reflashed for the tcm to pick the signal from the output sensor. problem is of course that will have to two a long distance to the dealer just to find out...not a great option.

will certainly post the final results here...in the meantime..any additional thoughts on the TCM etc are appreciated.

Btw, the scary part in all this, is that the bad connector i found, was visually fine. I grinded away the plastic and all crimps where good, wire was there, everything looked great and normal, but I am 100% positive it wasnt working when it was on my truck.

 

thanks for the link. It would have been nice if he had written back to say what theproblem ended up being for him.

Fire off a PM to him.......

 

Fixed The Problem

Ok, so i wanted to get back here and post the final fix, so that my thread may be a help to someone else.

The problem with my trucked ended up being two problems that happened at the same time. Murphy's law.

Problem #1: Connector 18" up the line from my output speed sensor had gone bad. Eliminated connector, and regained continuity to the tcm. When after i fixed the problem, as described above, my truck still had the abs light on, and would not shift out of first gear.
I reprogrammed my trucks computer using my bulldog power programmer. I just picked a random power setting, loaded it on, and after that the truck worked.

Problem # 2. The next day, my truck received the "shift range inhibited" message on the info pane. This problem turned out to be the ground lead that connects from the firewall, down to the back of the engine. THis ground lead is difficult to access on the engine side, because it runs downt he back side of the engine. So i bypassed it and ran a new lead to a pump mounting bolt.

Since this time, i have driven about 500 miles and not had an issue, so i feel confident that the problem is fixed.

Also, for anyone else reading this...before any of these problems, i was having issues with my heating and ac system sticking to one extreme temperature or the other...and the problem was independent per zone. I had gotten new actuators...and still not fixed the problem. SInce fixing the ground...problem with heating system is solved.

SO FYI everyone...if i were to buy another...or at least going forward...every so often i will just hedge my chances by redoing the grounds, before i get stuck towing somthing in the middle of the winter, in a bad situation. if i were you, i would do the same.

good luck

 

So I've got the same issue with no speedometer. I've had the vehicle speed sensor go out on this truck and replaced by the dealer a year ago. I heard that even the replacement ones were junk so I opted to just pick up another. I put that one in and no change. I cleaned and reinstalled the ground on the drivers side frame. No fix yet.

Does the front sensor have any play in the speedometer? Also is there a need to disconnect batteries to reset or a reflash of the puter to make things clear? I would think as soon as it sees signal the alarms would go away.

Any help for next test would be appreciated. Thinking the truck is on it's way to the dealer tomorrow or Monday.

 

There is a problem with the stepper motors going bad in the instrument cluster, that might be your problem.

 

Ya I'm on my second cluster as it is. My fear is that the replacement cluster could have gone bad. I'm not in the mood to keep trying parts as I don't have a lot of test gear. By the time I'm done I'd probably pay out the same as dealer to find the exact part and charge me a ton to replace it.

Last time my VSS was bad it was $250 at the dealer with labor. My cost was $56 for the part and 10min to R&R it. Although last time I was in remote country on an elk hunt so I had little options with what I could do.

 

Truck is at the dealer. Won't get worked on till Monday. We'll see what they have to say.

 

They found the TCM to be defective.


OUCH they are not cheap!!!!