if the wiring is in good shape the voltage variation shouldn't be that much,.5v at the most. If your getting more than that then you have bad wiring or bad connection somewhere, or worse case a bad carriage board. Also check to see if any of the height limit switches are around the height you specified earlier, maybe one of them is glitching the system causing it to throw the code. I'm still banking on the pot just being out of range but since I'm not there to see it for myself i cant say with any certainty.

Swoop, when I say sample the displayed voltage is not as accurate as following the readings through a Fluke 79, say. Also, those voltage readings pass though the handle harness, through the carriage control card, over the mast to the vehicle mgr, are processed there, passed BACk over the overmast cable into the carriage control card AGAIN and to the display for you to see...alot of room for error wouldn't you say?

kevin,
maybe i chose an incorrect term for that
yes ohming is a form of resistance checking but i use another method that was mentioned, a continuity check which also can show any resistance in the circuit. A good clean circuit will read close to 0 but if there is any anomaly in the path it will show a value greater than 0, basically the same as ohming does.

and as far as the A04 test it is there, when you get into the menu you can go to each segment and should be able to change it till it reads A04. I think when it first comes up it might read I00 or something like that if i remember correctly. Since i'm not looking at a manual right now or have one in front of me i'm trying to go from memory here.

joe,
and as far as the comment about not trusting the analog 'in-truck' tests? well this is what the truck is seeing and it reads that voltage to calibrate itself and guage the values on which the truck runs. The TMM is monitoring this voltage the way you see it there, so why wouldnt you trust it? Speaking of being bit, i've set many a potentiometers with a vom only to have to reset/readjust it after i installed it because the system was seeing it differently. Part of adjusting this and calibrating it to the system is having the test mode up on the console before you even remove the control handle from the circuit, if you try and set the pot externally and then start up the truck afterwards to go into setup mode to calibrate the system to it, the system will see this and will not start up correctly because it is not seeing the right voltage range and you will play **** trying to gain access. Sometimes the 'old school' ways just do not work, especially on these trucks.

Of course if this has the later system on it the access keypad/display is on the dash and not like the ones that have the remote display box mounted over the crossbar on the mast like the older ones, those require input solely from the control handle horn button and pot's, this being the only way to control the input to navigate the menu system. I'm farily certain they revised that keypad input to eliminate this problem that the older units had to simplify the calibration.

I've learned over the years to not depend on the in-truck analog tests as they only "sample" the voltages and I've seen many a tech that took these readings as gospel and got bit. Also, when I do an ohm test on an overmast cable I disconnect both ends, attach negative lead to say the red wire at one end and positive at the other. strum the cable like a guitar string at the point you think the problem is (this duplicates the bouncing around of the cable during lifting/lowering). If you have good continuity, disconnect negative lead and connect to another wire, leaving the positive on the red and repeat the strumming. Repeat this procedure through all the wires of the cable to verify that you aren't getting a short between wires that could cause your problem. I've had a truck lose wire guidance when lowering and honking the horn at the same time due to this.

"now from the sounds of it you may be in the right area but maybe your testing method for checking the mast cable is not correct? instead of ohming the cable wires try doing a resistance check instead. generally if there is a break in a wire there will be higher resistance that will show up that ohming may not."

Swoop,have one question on this statement Ohming and resistance checking are one in the same are they not? Ohms is resistance? Did you mean voltage drop test in this statement?

Here's an additional tidbit
I'd love to run the analog test A04 but it isn't an option in the analog test menu. I will be visiting this job again in the next day or so. I will note the software version and my avail
options for tests. FYI I do have both password and superword. And have been through all menus and am fairly proficient with these type of on board tests, and procedures.
Weather this info changes anything. But hey, if I can confuse anyone else over this unit, the better, the more the merrier lol. Thanks ahead of time for any input.
In the meantime I have ordered another OEM pot in attempt to rule out the most common failing part. I will follow up with any more info as I find it.

first off using 3rd party parts isnt always a good thing , always try and use OEM parts if availaible.

when installing the lift pot it is recommended to 'precenter' the pot to 653ohms, then using the below mentioned voltage ranges and having the truck in test mode set it center voltage of the expected ranges, the 653ohm range should have it farily close. Then once set run the learn mode test to calibrate the TMM to it.

secondly if your just testing then try going into the 'analog' test mode and go to test A04 and check the lift/lower pot voltage and see if it is staying within the expected ranges for this circuit which would be 0.156v - 4.84v , anything above or below this reading would trigger this code.

Also i noticed they have a revised OEM part number for the travel and lift pots, unfortunatly the service gram does not specify which one is which , i'm sure the parts person can determine this though when he checks the number
SE000258 and SE000267

the other suggestions for this failure would be:
incorrectly adjusted liftpot
control handle wiring may be faulty
bad carriage wiring board
mast cable (you already suspect this one)
learn mode needs to be run (you already did this also)
control handle may be moving beyond designed parameters due to a mechanical problem
and lastly a bad vehicle manager (lets hope its not this one)

now from the sounds of it you may be in the right area but maybe your testing method for checking the mast cable is not correct? instead of ohming the cable wires try doing a resistance check instead. generally if there is a break in a wire there will be higher resistance that will show up that ohming may not.

Just a thought

good luck