W124 e320 not engaging 5th gear

[boomtings]

my car will not change to 5th gear. What are the possible causes for this?

I found a thread somewhere , that stated to loosen the throttle cable by a turn. should i try this?

regards
Boomtings

 

[bolide]

4-5 shift is electronic and not affected by control cables

Nick Froome

 

[boomtings]

Thanks for the reply ,

Being electronic could my problem be a low charged battery ,causing electronics to keep engine revs high?

Regards.

 

[w124coupe]

Probably a daft question but you are sure this car has a 5-speed box?

 

[boomtings]

Hi , it is a 5 speed (or suppose to be!).

I recently had the torque convertor replaced, however prior to this i can remember around a year ago driving from London to Manchester and the car would not change to 5th, i was going to turn back near Luton but it changed up and worked properly (the only action i took to possibly influence this was to change the gear selector from D to 4 repeatedly).

Is my charging battery theory fantasy or did mercedes engineer this?

I hope its not costly as it seems the car is always eating cash in comparison to my ebay £1k 1991 E300 coupe.

Any help or advice is appreciated.

 

[w124coupe]

Good. In that case have a scrabble through this - it tells you how the electronics decide to use (or not!) 5th gear....

Given the disassembly needed for the new torque converter, you may have a wire off somewhere. I will start the bidding with the sensor that activates when the gear selector is in "D"...(its on the side of the selector box positioned so that its switched off when you move the lever sideways to be able to pull it into "4").

 

[bolide]

Good. In that case have a scrabble through this

Thank you - that's a useful PDF

Nick Froome

 

[boomtings]

Thank you for the pdf , I will have a good read, ive never really tackled any maintainance myself apart from window motor etc.

ill start with the selector switch when i have a chance , and work my way around.

 

[alexander patie]

hello there, it could be the microswitch in the gear change cluster as has been said above. it also could be a wiring connector near the battery somewhere that becomes corroded. these are both causes i have seen in the past.

another common problem is for the box to miss 4th gear altogether and go from 3rd to 5th, this is usually a solenoid valve inside the gearbox. i have done a couple of these but not for some time!! can you be sure it is missing 5th? is it perhaps just skipping 4th? it should be obvious by the difference in engine rpm.

i believe this g.box does have a control unit which can output fault codes. it is feasable to diy this with nothing more than an led and some wires.

 

[kth286]

No gearbox codes on this model.

 

[kth286]

I have now looked at the attachment in a previous post and it talks about the EZL control unit.

Your E320 convertible does not use the EZL system on your HMF engined car so that attachment is not appropriate.


Do determine if your box goes from 3 to 5 OR whether it really does stick at 4 and does not get into 5.

Let us know which it is.

 

[w124coupe]

The HFM versus EZL differences are in how the roadspeed (TN) and load (related to intake vacuum level) signals are transmitted - both come from HFM ECU instead.

Re "what gears have I got?", here's the Merc method:

 

[w124coupe]

If the box is missing out 4 (i.e. changing 3->5) then check the solenoid connection at the box was reconnected.

If its not going into 5th then start with the "D" switch on the selector as the simplest possible cause.

(all on the assumption that something was missed/damaged during the repair)

 

[w124coupe]

From your description and history, I still bet on the "D" switch at the selector as the culprit.

 

[ray_hennig]

3rd to 5th - Very Interesting

Sorry to hijack this but I have a 3rd to 5th problem in my 300ce-24 with the EZL and KE-Jetronic. 4th is there but it only engages for a millisecond.

I also have downchange reluctance.

Any ideas gratefully received.

All the best.

RayH

 

[boomtings]

I have now looked at the attachment in a previous post and it talks about the EZL control unit.

Your E320 convertible does not use the EZL system on your HMF engined car so that attachment is not appropriate.


Do determine if your box goes from 3 to 5 OR whether it really does stick at 4 and does not get into 5.

Let us know which it is.

its sticks in 4th and will not change to 5th

 

[alexander patie]

elaborate please boomtings, how do you know for sure? please tell the rpm before and after the change.

also, have you tried everything/anything suggested?

 

[alexander patie]

No gearbox codes on this model.

au contrare kth286, the blink codes can be read with an LED at the 16 pin connector. have a read of the pdf...............

 

[kth286]

au contrare kth286, the blink codes can be read with an LED at the 16 pin connector. have a read of the pdf...............

Not for the gearboxes on 124s.

There is no pin in the 16 pin rectangular diagnostic socket.

On 129s and 140s only.

 

[alexander patie]

i have read them on 124s!! pin 11. obviously it is only for the 5-speed box and only regarding the 4-5-4 changes, but hey don't believe me, here it is - page 11.

http://www.motodok.com/Documentation/Files/MB/cs1000-mb.pdf

these 5-speed 124s are fairly few and far between, and the gearboxes in good condition are sought after. our preffered specialist repairer used to pay good money for s/h ones to dismantle for parts.