Doosan DA30 with ZF 8EP 320 Transmission goes into neutral whiles driving.

[Brian Bobb]

Can someone help me to figure out what is causing it to go into neutral? You can then shift it back into gear but it will go back into neutral less than 5mins. Could a solenoid be bad in it?

 

[Bigbert]

Hi Brian,

there must be a fault code somewhere on dash indicating reason for shift to neutral.
Any chance to get a readout of fault memory of TCU?

 

[Brian Bobb]

Yes there was a fault code for the exhaust brakes being out of calibration. How can I go about to get the fault memory of the tcu without a scanner?

 

[Bigbert]

Brian, how was the code in digits?
Readout fault memory usually from ZF technician, Doosan expert should also be able.

 

[Brian Bobb]

Brian, how was the code in digits?
Readout fault memory usually from ZF technician, Doosan expert should also be able.

Sadly we do not access to those at the moment to get the readouts

 

[Bigbert]

Did someone exchange engine controller or transmission controller recently? Do these two units fit together?

 

[Brian Bobb]

The ECM was not exchanged but the TCM was exchanged to see if that was causing the issue but it did the same with the other TCM.

So checked the exhaust brake actuator and the wires were damaged from the heat. Repaired the damaged wires and it stop doing that. I honestly cannot understand how that was affecting the transmission.

 

[Bigbert]

Hi Brian,

so congratulations. And thanks for feedback what many members miss after issue is fixed.
Reason for affect to tranny: The clutch pressure during shifts is calculated mainly from engine and engine brake (when engaged).

 

[Brian Bobb]

Hi Brian,

so congratulations. And thanks for feedback what many members miss after issue is fixed.
Reason for affect to tranny: The clutch pressure during shifts is calculated mainly from engine and engine brake (when engaged).

Thank you guys also for your input.

Oh so that is why it would affect the transmission. Though the funny thing is, we have another truck that has the same exhaust error code and it drives without any issue. Then again that one actuator wires weren't damaged by the heat.

 

[Bigbert]

Hmmm, strange.
ZF usually got very specific codes, broken wire, short circuit, low resistance etc. How Doosan puts it into clusters and throws similar codes I'm not aware. Engine brake torque is mainly important during coast (brake) downshifts, (coast upshifts are seldom).
Any chance to erase the fault code? Or when does it become active?

 

[Brian Bobb]

Hmmm, strange.
ZF usually got very specific codes, broken wire, short circuit, low resistance etc. How Doosan puts it into clusters and throws similar codes I'm not aware. Engine brake torque is mainly important during coast (brake) downshifts, (coast upshifts are seldom).
Any chance to erase the fault code? Or when does it become active?

Yeah I recall they have specific codes for almost everything.

So the problem came back again. This time it has a transmission error code that doesn't stay on for long, SPN 523650 FMI 0 OC 31

 

[Bigbert]

Hi Brian,
according to my documents: TCU got a neutral signal while truck in motion. Check wiring/plugs from/to gear selector.

 

[Brian Bobb]

Thanks for the response. I checked the wires from the gear selector to the VCU3 box and they are all good. Is there another way it could get a neutral signal?

 

[Bigbert]

Does it drop to neutral when running over bumps or accidentially?
Any other feedback from operators?

 

[Brian Bobb]

It just drops into neutral like that. No bumps are anything like that to cause it to. Even when you have it in manual mode, it goes into neutral. At first the operator thought that when it reaches 4th and higher gears, it goes into neutral but it does it in all the gears.

Had a meter hooked up to the neutral wire to see if power was going to it when driving but no power goes to it even when the dashboard shows it goes into gear and the gear shift lever is still in forward.

Whenever it does into neutral while driving, there is an alarm but no error codes except for when 523650 finally showed itself but not every time.

 

[Bigbert]

Would you have the chance to swap gear switches from a good to bad truck?

 

[Brian Bobb]

Yes, swapped gear shift, tcm and even ecm and still getting the same neutralising during driving. Even swapped the vc3 lol

 

[Bigbert]

So, I'd assume the issue is somewhere between gear shift connector and plug to transmission.

 

[Brian Bobb]

So, I'd assume the issue is somewhere between gear shift connector and plug to transmission.

Alright I will have to raise the cab and check the wires to the transmission. Is the neutral power from the gear shift converted over to can bus data to the tcm?

 

[Bigbert]

Presumably the gear shifter is giving digital signals to VCU (vehicle controller), which gives CAN signals to TCU.