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Caterpillar CX28 coupled with CAT C9 engine...gear shifting issue

bill.townsend

New Member
Joined
Jan 21, 2017
Messages
2
Location
London
Hello all I am Bill Townsend from London,UK. I have CX28 Caterpillar transmission and it wont shift from 1st gear. It is only shifting in 1st and reverse gear and neutral. It will not shift to 2nd 3rd and so on. Please suggest what possible problems can be stopping the transmission to shift. I did a little bit research and found the following aspects that might be effecting it;

1- Oil cooling system not complete? (note: the cooling system that is the heat exchanger and auxiliary fans are disconnected and bypassed)
2- How does the cooling system switch the auxiliary fans to operate and what controls it?
3- Lockup clutch not engaging? (What possible things that can inhibit the ecu to not engage the lockup clutch)
4- accelerator pedal WM526 not calibrated? (How to calibrate and make sure it is rightly calibrated)
5- Engine RPM?
6- Transmission Oil pressure?
7- Transmission Oil filter blockage?

Please suggest more and please suggest actions how to check for the above mentioned issues.
 

Nige

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Jun 22, 2011
Messages
28,974
Location
G..G..G..Granville.........!! Fetch your cloth.
Having thought about it a little more there is always the possibility that the output speed sensor signal is bad/missing. The transmission will not shift past 1st gear forward under those circumstances.

The bad news appears to be that to diagnose the electronic side of a CX28 transmission in order to identify any Diagnostic Codes will require the use of Cat ET. There does not appear to be an option to use any other type of Service Tool such as a Click Box.
 
Last edited:

bill.townsend

New Member
Joined
Jan 21, 2017
Messages
2
Location
London
Having thought about it a little more there is always the possibility that the output speed sensor signal is bad/missing. The transmission will not shift past 1st gear forward under those circumstances.

The bad news appears to be that to diagnose the electronic side of a CX28 transmission in order to identify any Diagnostic Codes will require the use of Cat ET. There does not appear to be an option to use any other type of Service Tool such as a Click Box.

the powerpack is installed in 6x6 truck chassis....s/n for xmsn cx28 is tbb1UP
well i will check the speed sensor on the xmsn. any possibility the issue is because of xmsn oil?
 

Nige

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Jun 22, 2011
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G..G..G..Granville.........!! Fetch your cloth.
There's the possibility of a lot of things. However although you seem to have investigated the possible root causes on the internet how much work have you actually done on the transmission itself..?

Also give some more information on how the problem came about. Did it happen suddenly or has it been getting worse over time..?

Unfortunately without ET you're going to be pi$$ing in the wind trying to diagnose the electronics.
 

Nige

Senior Member
Joined
Jun 22, 2011
Messages
28,974
Location
G..G..G..Granville.........!! Fetch your cloth.
I would check the rpm sensor and connector first. Who makes the transmission controller Spicer/Dana or Funk?
The ECU is made by Cat and runs Cat software.......the transmission ECU interfaces through a J1939 Datalink to the shifter, engine, ABS, etc, and through a J1587 Datalink for the OEM gauges.

the powerpack is installed in 6x6 truck chassis....s/n for xmsn cx28 is tbb1UP
So if I'm reading it right this is the mil-spec version of the CX28 complete with transfer case, correct..?

Bill, How much technical information do you have on this transmission at the moment..? I can probably help you with things like an electrical schematic and System Operation documentation. On the Troubleshooting side the top of the tooling list is Cat ET, having looked through everything I can't see any way around it.
 

Mark250

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Aug 30, 2015
Messages
1,243
Location
victoria,Australia
Occupation
heavy equipment technician
Hi, before I say anything I will state that I have never seen one of these before but i have been able to read up on its operation on SIS
do you have the amber and red fault lights installed and are they lit
is there a light on in the shifter i believe it is the mode light according to sis. it can be programmed to first gear forward and reverse only .and can be changed by varying the length of time that the mode button is pushed
Other wise i agree with Nige that you will need ET to troubleshoot this tranny
Mark
 
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