Monday, October 25, 2010

Allison Automatic Transmission Troubleshooting MD 3060 Code 2116

The Allison automatic transmission MD 3060 is all electronic running off direct battery power to a series of relays, fuses and modules. The ECU (electronic control unit) for the transmission reads and controls inputs and outputs. Inputs include engine speed, output speed, turbine speed (the trans internal drive shaft) and throttle position. It computes these inputs into smooth shifts according to these variables.

The TPS Cable Complete - It's Located In The Engine Compartment Area

If it receives a bad signal everything goes to hell in a handbag. Code 21-16 is a trouble code for the Throttle Position Sensor. One of my newsletter subscribers from North Carolina has a 1996 Holiday Rambler motor home with a 5.9 Cummins diesel engine. He's dealing with this code and asked me to help him out.


The TPS control has 3 wires to it, one sends a 0 to 5 Volt signal to the ECU which regulates shifting patterns using these voltage readings. Full throttle and idle can be determined this way, if the wrong reading is sent then you will get a hard shifting scenario.The other 2 wires are the battery voltage and ground.

21-12 Code indicates that the ECU is receiving 14 counts or less. The TPS works with counts and 14 is too low so the problem might be at the closed throttle end of the TPS travel. The first check to make is the cable for frayed wires hanging up somewhere or a bad wire in the 3 wire harness.

My Crude Wiring Diagram Showing The Simplicity Of The TPS Circuit.


I've seen a couple of bad cables and have also replaced all three wires from the TPS to the Trans. ECU. You can check the wires for grounds, shorts or open circuits. If you replace the TPS you can reset it by cycling the ignition 5 times to reset the 0% and 100% throttle position or use the 'ProLink' Reader to reset the system.

10 comments :

Dariusz said...

I have a problem with a Krupp 3050 all terain crane with the Allison Gearbox 3060P.
Would you help me?
Could you advise if it is possible that TPS signal or no TPS signal may cause the following problem with no gear shifting?

In November we changed oil in the gearbox to ATF Dextron II without changing the filters.
We took off the filters but we din't find a new one so used the old one.
(We filled the gearbox through the pipe with the measure with the chassi and checked the level at the measure not at the shift selector)

Two or three weeks later in the morning when the crane started to drive it shifted to the second gear and immediately came back again to
the first gear. "Do not shift" lamp lighted on.

The "do not shift" indicator didn't come on again. it is on only before the engine start then is off.

Since this situation we were able to drive only the first and the reverse. The crane drove well on these two gears.

At the shift selector there was only one error d1 21 12 - THROTTLE POSITION SENSOR, FAILED LOW.

So I focused on this error. I'm not sure if this error had been before becouse I had never checked errors before.

We meansured the acceleration pedals and resistant were ok. The resistan of the acceleration pedal comes to the Heinzmann
unit was correct. We meansured voltage coming from the Heinzmann unit to Allison TPS input (TPS singal comes from the Heinzmann unit directly to Allison ECU)

It seemed to be ok but I checked only voltage not a shape of the signal.

I was confused and I ordered mechanics which should be familiar with ALLISON gearbox. They are authorized by Allison.

Unfortunatelly there came in the evening, my crane worked on site and they were hurry.

They pluged computer to the Allison ECU and connected with the computer. They found only d1 21 12 - THROTTLE POSITION SENSOR, FAILED LOW.

They said that the signal is two low becouse it is not about the signal but it is about the shape. They claimed that the gearbox should shift even without
TPS signal and if the signal is bad it is recommended to even plug it off from Allison.

We checked with and without the TPS signal and was the same. Then they try to shift the gear directly from the computer. It failed.
They said that there must be the secure (governor) if the crane is set up for work with the tele out or tele raise.

They asked to bring the crane to the drive position and then they tried again. They shift to the 3rd gear and said that the gearbox worked at 3rd gear
so I must be everything with the gearbox and the ECU. They said that there must be the secure (the governor) in the Krupp electric but they are not
familiar with the Krupp and has no time.

They had a problem to turn off the 3rd gear. I was no worry about that in those days.

After diagnose I checked signals coming to the Allison VIM and The Allison ECU. All seem to be OK.


When the gearbox is shifting to the 2nd gear you can observe digit 2 at the shift selector for a short while, then it changes to the 1st gear.
You can feel the engine stops the gearbox and the crane brakes.
The crane can drive only 5-7 km/h if "6-1" is selected. It can drive 10-12 if "1-1" is selected.

I don't think there is a problem with the governor of the Krupp instalation as they said.

Could you advise?

Anonymous said...

Need help troubleshooting MD3060 code 5644. Also an Allison Auto Trans.

Automatic gearbox repairs said...

Great content! This will aid some people find out about this matter. Do you want to incorporate video clips along with these? It will undoubtedly help out. Your reason was spot on and owing to you; I probably won’t have to describe all sorts of things to my pals. I could just lead them here.

ilya korogodsky said...

Have the same problem on my routemaster. Can you tell me where can i find throttle linkage? As shown on your scheme.

Will be glad to hear you soon

Thank you

Brenda said...

MD3060 The CheckTransmition Light Stays on its giving me the codes D1 34 12 the engine starts will not go into gear.I n a 1994 foretravel uni coach motorhome need help diagnosing any suggestions greatly appreciated

Brenda said...

MD3060 The CheckTransmition Light Stays on its giving me the codes D1 34 12 the engine starts will not go into gear.I n a 1994 foretravel uni coach motorhome need help trouble shooting any suggestions greatly appreciated.

John Whelan said...

Hello Dariusz

Failed low is the ground side of the TPS and they do fail but I would trace the wiring first and if all else fails replace it.

Brenda said...

YES PLEASE I unhooked battery turned key went back hooked battry up again. Here to let U know I am a blonde didn't see a grey wire for the neg.post so put that on. Read somewhere these wire go to Ecu and to tran so follower them wires go down and other ones go up and thru the wall toEcu and other coming out of toggle switches that go along bottom of engine compartment wall towards the coach batteries and go to nothing.So I turn the key 5x's without starting and pressed the brake 3x's and started it.The WTEC11 shift pad says " MODE 8 with a slash from left top to bottom right,ir could be a 0 but looks more like 8. Push the up and down arrows twice get the same codes D1 34 12. Could the wire going out of the engine compartment be a ground ? It has a round flat contact that could mount to the frame. And would that give me the coDe D1 34 12 the other 4 drives are -- -- blank. I would appreciate any help. Thanks Anonymous, Brenda


Brenda said...

Also forgot the Check Transmission Light Still On

John Whelan said...

34-12 is an eprom issue http://www.jultech.com/products.html

Allison's ATEC Electronic Control Unit (ECU) is able to adapt to many different applications by a removable "Erasable Programmable Read Only Memory" (EPROM) microchip to change the ECU’s behavior. ATEC ECUs are also called CEC1 ECUs.

Was your trans ECU replaced by any chance?