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Billy
Billy, Trainer/Master tech.
Category: UK Car
Satisfied Customers: 3498
Experience:  Trainer - master tech., SAE member
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We have a Mitsubishi pajero 3.5 ltr GDI , with a gear

Customer Question

hi We have a Mitsubishi pajero 3.5 ltr GDI , with a gear shift problem. The gearbox seems to be in Safe mode . It goes into reverse fine , but when you put it into Drive it jumps straight into 2nd gear. Even if if you try to select the gears manually no
joy. Have plugged my diagnostic machine onto it and there are no fault codes. Took it to the Mitsubishi agents for diagnostic, also no fault codes . The only fault code we getting is a fault on the transferbox . Could a transferbox fault put the auto-gearbox
into safe mode ? Could an engine fault, like a cat sensor put the gearbox into safe mode ? I took the box out, split the transfer case and bolted a second hand gearbox to it and fitted back, still doing the same thing. When reading live data with the diagnostic
machine, notice that the g/box oil temp stays at -40 degrees and that there 0 reading from the input shaft and output shaft speed sensors, so i borrowed a engine/gearbox ECU , fitted it and the problem is still there. Dont know what to do now!!!
Submitted: 1 year ago.
Category: UK Car
Expert:  Billy replied 1 year ago.
Hello and welcome! I'm Billy and i will assist you with this. Feel free to ask if further info is needed.
As checked and confirmed by yourself, the transfer case should not cause such a problem.
However, let's confirm a few things:
- do you have the check engine light on?
- when accessing the trouble memory in the transmission unit, are you able to access, or you have a no communication issue?
- which year is this pajero?
Customer: replied 1 year ago.
Hi BillyNo check engine light on, when i first got the vehicle the check light was on, code was for a cat sensor, but cleared it over months ago and it has never resurfaced. The lady who was driving the car didn`t realise it was staying in 2nd gear so i think she over reved it, which is why the cat sensor came up.
Have a Launch diagnostic machine so can scan for faults and even monitor live data , but not getting fault codes. Even at the Mitsubishi, they got no faults.
What do you think about there being 0 revs at the input and out out speed sensors, and -40 at the atf temp sensor?
Expert:  Billy replied 1 year ago.
Which year model is this?
Customer: replied 1 year ago.
the year on the seat belt is 1999. Model - 6g74 , with SS4II
Expert:  Billy replied 1 year ago.
Hello,
The problem is with the data you are getting (no temp, no revs).
If the launch is accessing correctly, i would first check the wiring to the control valve (valve body), as the sensors, and solenoids are in there, and they should link to the transmission module to operate. It seems, they are not. This would be the first thing to check (wiring and connectors from the transmission module to the valve body assembly.
Kindly get back to me with your findings, so we proceed as necessary.
Regards,
Billy
Customer: replied 1 year ago.
I already change the gearbox, and with the diagnostic machine i can activate the each valve in turn and hear them coming on and off. I will try trace the wiring from the speed sensors to the at -ecu tomorrow and see if there are any breaks . What i did notice the other day was that while running live monitoring , i was getting the same reading from both speed sensors even if i disconnected them. When they were disconnected i was also NOT getting a fault code which i found very strange, this is why i thought it was the ENGINE/AT ECU, but fitting another 1 didn`t help.
Expert:  Billy replied 1 year ago.
Hello,
Having both reading zero (same rpm) sometimes does not trigger fault codes.
The wiring is known on some of these model to cause endless problems. And it would also cause exactly what you're experiencing, so i would remove the wiring harness for the A/T and check it thoroughly.
Regards,
Billy
Customer: replied 1 year ago.
Thanks BillyI will go thru it tomorrow and let you know what i find
Expert:  Billy replied 1 year ago.
You're most welcome Sir!
Best of luck for now...
Customer: replied 1 year ago.
Hi BillyUpdate , I got a friend of mine who is auto electricain to come give me hand today . He checked/tested all the wires from the gearbox to the a/t ecu and found no breaks . We then simulated a fault by disconnecting the a/t relay and plugged the diagnostic machine on , and we got a fault code for the relay and much to my suprise the gearbox went into 3rd gear. Once we plugged the relay back and cleared the fault code, the box when back to its old system of 2nd gear. So we learnt that safe mode for this model of gearbox is accually 3rd gear not 2nd , so the box is not in safe mode, which explains why we are not getting any fault codes. Even if you turn the ignition on and move the gear leaver to drive, it jumps straight to 2nd gear. Moving it from `d` to manual select up and down makes no difference!
What could cause a box to behave like this / Remembering i have already changed the gearbox and engine/at ecu...
Is there another control box we should be check, maybe in centre consol ?
Expert:  Billy replied 1 year ago.
Hello again,
Those are some very clever diagnostics....
In your case, i would first check the transmission position switch.
It is on the auto transmission box, where the shifter cable attaches.
I will include some details (about when it gives conitnuity) so you check it. If this is good, and have no problems, then you need to check the wiring between this and the control unit. Then i would remove the shifter lever itself, and check for any water ingress on its wiring...
In my opinion, the most likely cause is the switch to be checked, however get back to me with the findings: here are the details:
https://drive.google.com/file/d/0B6Zgf4dbmODzVEF5RnVXcEFhOEU/view?usp=sharing
Kindly get back to me with the results (hopefully the fix), or if further info is needed.
Regards,
Billy
Expert:  Billy replied 1 year ago.
Hello,
when you say you move it from D to manual select, does that mean that you have the shifter lever move sideways? (prnd, and manual on the other side)?
If yes, that would be the newer model, and the problem would be the shifter assembly (it has an integrated module inside), in which case, i would remove the shifter assembly, check its wiring, and if wiring and connectors are good (no signs of water ingress or coffee etc..) then the shifter would require replacing, and it should sort the problem
Regards,
Billy
Customer: replied 1 year ago.
Morning Billy
Thanks for the info , yes correct ,lever moves down from PRND , then shifts left for manual select up & down.
We were abit stumped yesterday when i sent you my response, so while we waitedfor ideas from you , we decided to remove the centre consul by the gear selector lever. Suprise suprise , we found a rat had made his home under there!
There are another 3 control boxes under there and millions of wires. Today we will start to check all wires there for rat damage, hoping to find only broken wires , not shorting wires that have damaged a control unit .
Do you know what controllers they could be ? I`m guessing 1 is ABS MODULE , the other is TRANSFER ECU , but no idea on the 3rd .
Expert:  Billy replied 1 year ago.
Hello,
This rat couldn't've picked up a worse location... The SRS (airbag) control unit should be in that location as well.
For confirmation, you can send me the control units' part numbers.
Hopefully there are no shorts, only some disconnected wires...
Best of luck for now! And get back to me with your results, or if further info is needed.
Regards,
Billy
Customer: replied 1 year ago.
Thanks , will do
Expert:  Billy replied 1 year ago.
I will be waiting for the results... some good news hopefully...
Customer: replied 1 year ago.
Hi BillyWe still working on the problem , so mite still need your help further , do you want me to rate your answer now or when we done ?
Expert:  Billy replied 1 year ago.
Hello,
You can rate whenever you want.... I'm here, just get back to me whenever assistance is needed on this.
Cheers!
Customer: replied 1 year ago.
Hi BillyI found a broke wire under the dash , which once fixed, allowed the box to go to 1st gear . Its taken the whole day , but got the dash back together and took it for a test drive . I had gear change thru all gears ( a bit of a lag/ rough gear change ) and as i was getting excited the box went into safe mode . I put the diagnostic tool on and got 4 fault codes - code 41= 1st not syncromesh ; code 42 = 2nd not syncromesh ; code 43 = 3rd not syncromesh ; code 44 4th not syncromesh .
Any ideas what this is about , is it a setting somewhere ?
Expert:  Billy replied 1 year ago.
Hello,
If the output from the output shaft speed sensor multiplied by the 1st gear ratio is not the same as the output from the input shaft speed sensor
after shifting to 1st gear has been completed, diagnostic trouble code number "41" is output. If diagnostic trouble code number "41" is output four
times, the transmission is locked into 3rd gear as a fail-safe measure, and the "N" range light flashes once per second. Same for 42, 43 and 44.
Having all four codes, and if you are sure of the wiring (i would triple check in your case, all the wires from shifter to PCM and to gearbox), then the most likely reasons would be:
Malfunction of the input shaft speed sensor
Malfunction of the output shaft speed sensor
Malfunction of the PCM
Malfunction of the underdrive clutch system
Basically the system is slipping, as incorrect ratios are being detected. This would be caused by the detection system (speed sensors), or the hydraulic system (valve body, converter, clutches for underdrive).
This is not a setting, i'm afraid. This is the gearbox slipping. Checking the oil (also if low might cause this) for burnt smell, or particles (from slipping clutches) would confirm a hydraulic issue if any.
This is the gearbox from hell, you got there... Don't worry, i will stick with you, until we have this thing operating as it should.
Regards,
Billy
Customer: replied 1 year ago.
Morning BillyI started with the input and out put speed sensors , as i thought they mite have been damaged with us replaceing the gearbox . Unfortunatly i dont have access to an osilloscope , so manged to find 2 second hand speed sensors and replaced them , but still code the same fault code . As i already had a spare pcm or a/t ecu , i changed that and still got the same fault code.
I have done activation tests on valve solinoids and can hear each one in turn , some louder than others .
The oil level is good and clean .
Any ideas of what to check next.
I was thinking to drop the gearbox sump and check the filter is clean and maybe drop the valve body and clean and test each valve , as this is a second hand box from japan, and maybe if it sat for a while, the valves mite be sticking ?
From there i`m completely at a loss again , after i thought we had the problem fixed 2 days ago...
Expert:  Billy replied 1 year ago.
Hello,
If the speed sensors are good, then the gearbox is slipping.
I do presume that you have the same gearbox (part number) installed.
Having said that, indeed, the next step would be checking the cleanliness in sump, filter, and solenoid valve checking (dropping and cleaning the valve body).
A slipping torque converter or a worn pump would also cause this. But let's take this one step at a time... Hopefully the next step will clear the issue.
If, having done this the problem persists, try swapping the valve body from the older box, that is in the older gearbox.
Get back to me....
Cheers,
Billy
Customer: replied 1 year ago.
Hi BillyI have dropped the valve body and all looks good . I did notice that this valve body has more valve accuators than the previous box , would that cause the problem we are having ?
Expert:  Billy replied 1 year ago.
Hello,So it's not the same gearbox. Indeed that might cause the problem. As the transmission control module is detecting different ratios. A different gearbox, even if good, would have different ratios and cause all these codes (slip codes).
Customer: replied 1 year ago.
Sadly i think you right . the box was identical on the outside, and only noticed the difference internally once i opened it . Unfortunately i had already sent the other box away , so will have to get it back. Will let you know once i get this done. Thanks
Expert:  Billy replied 1 year ago.
Take your time.... and best of luck ... you need a break on this already.