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?
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?
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?
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
Did someone exchange engine controller or transmission controller recently? Do these two units fit together?
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.
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.
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
Hi Brian, according to my documents: TCU got a neutral signal while truck in motion. Check wiring/plugs from/to gear selector.
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?
Does it drop to neutral when running over bumps or accidentially? Any other feedback from operators?
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.
Would you have the chance to swap gear switches from a good to bad truck?
Yes, swapped gear shift, tcm and even ecm and still getting the same neutralising during driving. Even swapped the vc3 lol
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?
Presumably the gear shifter is giving digital signals to VCU (vehicle controller), which gives CAN signals to TCU.
So something is telling the tcm to go into neutral while driving. I've already checked from the gear shift and everything is good from that end to the vc3. I will check the wiring from the vc3 to the tcm and transmission. Is there anything else that can cause the transmission to go into neutral while driving?
Hi Brian, are you able to share TCU number/code? And have you any chance to get a readout of fault memory of TCU/ECU/VCU? Possibly the output speed signal is sometimes faulty. But this one is wired up internally. So not quite easy to fix in truck.
I will attach the TCU info. I wasn't able to get a scanner as yet to pull the codes. Should be getting one later this week. So if it is the output speed signal, the entire transmission has to be taken out to get access to it?
Due to the adapter for the scan tool taking a while to come, we had someone come to test the pressure of the transmission and it turns out that the converter was losing its pressure.
Brian, I'm not sure what came first? Hen or egg? Losing converter pressure: Is it lockup clutch (LUC) pressure? Or converter back pressure? Presumably lockup as converter pressure is created via mechanical spring and piston. The question is: Does LUC disengage due to transmission going to N (A) or vice versa (B)? Rather situation A. I'll share a few pics from output speed sensor in a conversation. Space in DA 30 is pretty tight, so not sure whether you'll have easy access.
Thanks for the response. I was not at work the day the guys came to hook up the pressure gauge to say that it was the converter that is losing pressure. Apparently they did not specify if it was the lock up or back pressure. The thing is, the truck is still running without any issues so far.
Just want to give an update. Even though there was no fault code for it, the harness for the mass air flow sensor had the wires broken internally. Had a guy come to check it and said their dealer had an use with it. The guy only checked the ohms which was ok. I decided to pull on the each of the wires and the power and signal wires were left in my hand lol. Repaired them and the no more jumping into neutral.
Brian, this is very valuable info. Thank you for update. Only a few members give feedback after fixing the issue. This is a real pity.
I do apologise for the lateness in replying due to work being busy and being so damn tired. This forum has been a God sent to me that I am obligated to post an update for others to see so that it might help those in the same position. Yes it is a pity that only a few would do that. Thank you guys for all of the inputs. I really appreciate it.