E53 3.0 diesel no reverse, drives forward in neutral
 

Hello,

Recently I have bought an 2003 e53 3.0 diesel with transmission issues. It has GM 4L50E transmission.

Car seems to drive forward normally. Shifts up an down no problem but has no reverse and drives forward when neutral is selected. In between shift from park to reverse car tries to move forward, then stops abruptly. Behaves like if it was in park when throttle is applied in reverse. No transmission safe mode is shown on display.

Diagnostic shown 0 trouble codes in TCM but I am unable to connect to ECM. Also the check engine does not light up when I put key into second position.

I have removed the tansmission oilpan and checked the linkage and manual valve. Everything seemed normal no debree or metal inside, oil was not burned. After that I have removed the valve body and replaced it with one from used transmission that was slipping but was driving forward and reverse. Also replaced the range switch inside transmission. All of this made no change at all and car is behaving the same.

Also I have disassembled the original valvebody. All solenoids were functional no contamination inside. Valves OK. But 3 out of 4 springs in the acumulators were broken into pieces.

I would greatly appreciate any advice on whether should I remove transmission and look for internal problem or there is possibility of this problem being electrical.
There are signs of water corrosion on contacts of tcm but it seem old and car was supposed to drive fine just weeks ago.

Thank you all very much
Best regards Samuel

Is the gear position showing correctly on cluster (that information comes from EGS via CAN-bus)?

Yes, cluster and leds next to the gear lever are showing all gears correctly including S and manual shifting.

I think you’ll find that you actually have the GM 5L40-E transmission.

I agree that you should eliminate a possible electrical or electronic issue first, so I would recommend that you temporarily disconnect the 20-pin connector at the back of the transmission to deliberately put it into failsafe mode. Once in failsafe, Park, Reverse, Neutral and Drive (5th gear only) should all work under purely hydraulic/mechanical means without any electrical or electronic involvement. If you’re still having the same issues, then you have an internal problem with either the hydraulics or the mechanical running gear which will require the transmission to come out of the vehicle for investigation. Note that in failsafe, gear selection is harsher because there’s no line pressure modulation.

Phil

Thank you for response.
I have tried disconnecting gearbox but it will not start without that round connecor connected

Okay, so I have disconnected transmission on running engine. It went into protection mode but gearbox is behaving the same. Nothing in reverse and driving forward in neutral. So it is probably shot.

I am still unable to connect to ECM. It will detect it and show its details but I cannot read DTCs or look at live data. Always getting no response error.

Other modules like TCM or airbag are reading okay.
I am using Launch 431 scanner.

Any ideas on that?
Thanks

Sorry, my bad. I’m was thinking of the ZF 5-speed transmission which has an external inhibitor switch on a different loom. The GM switch is internal, so it is wired through the 20-pin plug.

Phil

Is the physical linkage the issue: I have a client who's e90 is just a little off: the car will be in N when you select R. You need to pick R+ (push a little farther) to get R. What you described above sounds very similar.

I have literally watched the spring loaded pin going right into its notches for each gear with oil pan removed. Linkage is working fine.

I have managed to connect scanner to ecm finally. Just had some settings wrong. Nothing there except glow plug.

I have tried all of the solenoids inside gearbox using scanner with my ear on the oilpan. All of them made audible click except "solenoid 2" I have tested all solenoids when I had valvebody outside gearbox so this can possibly be an problem either in the wiring or TCM. Can this cause my geabox not to go into reverse ?

I am unsure as I have tried it without electrical connection what so ever and it was doing completelly same thing.

I will probably slap used transmission in it. If it doesnt fix it I am breaking that hooptie for parts

Check out this link you don't have reverse.

https://www.bimmerfest.com/forums/sh...d.php?t=458451