Urgent assistance needed, anyone have access to W124 wiring diagrams?

[Lewis 2.3 16]

Hit a bit of a brick wall trouble shooting a W124 300TE-24v which doesn’t shift into .5th gear, it’s 722.5 transmission (electronically controlled 5th gear/OD). I am getting 6 and 9 blinks on the LED fault read out. According to WIS right front wheel speed sensor is responsible for 5th gear, if a signal speed is seen at 80kmh or more the trans will shift into 5th I’m getting a 3v alternating pulse at right front wheel speed sensor but nothing at the transmission control module.

I am asking if anyone can help in sharing a wiring diagram for the transmission control module and the ABS control module on a w124 300-24v equipped with 722.5 transmission.

Any help will be much appreciated

 

[optimusprime]

Google images will show you as many diagram that you will need .

 

[Lewis 2.3 16]

Hi Optimus, I have looked and looked on the internet an can’t find specific circuit diagrams for a w124 m104 engine with 722.5 transmission, it was only in the w124 for a short run so there is very little available info on the internet.

Anyone have any links or point me in the right direction?

Thanks

 

[ray_hennig]

if a signal speed is seen at 80kmh or more the trans will shift into 5th

Not strictly true, I think. If you are in "S" setting, yes. If you are in "E", it shifts to 5th lower.

Are you sure it's not shifting into 5th? I ask because mine used to jump 4th (half a second or less in 4th?), straight to 5th. It was because the 4th/5th switch was intermittent and this logged an error. I can't remember the number of blinks.

I cleared the code several times and that would clear the problem until the switch would act up again. New switch and cleared error solved the problem.

I too am trying to find wiring diagrams and it ain't easy for we 300-24 boys.

Bon courage.

RayH

 

[WDB124066]

There is an electrical switch that plays up outside of the box by the shifter that will stop a 722.503 from engaging 5th.

I think I may have one, do you have an email address, file size is too large to post here.

 

[WDB124066]

I've just recieved a message...

Trans won’t go to 5th.

5th Gear won't engage - Page 4 - Mercedes-Benz Forum

You will find a switch usually on the shifter, but on some it is a standalone switch on the consol. This can easily be tested with a multimeter. These trannies, also need to get 4 or 5 other signals before 5th engages. These signals include engine speed, load, vaccum, and throttle position.failing to shift to 5th can be a result of a faulty cam angle sensor which supplies engine speed data to the ECU, a faulty vaccum check valve( these are located on the inner firewall and have 2 or 3 vaccum attachments and and a twin wiring connector, a faulty ECU or MAS, or even a bad ignition module or simply a cracked vaccum hose can have this effect. There is also a hydraulic solenoid valve in the tranny for 5th gear which often fail. They were after all the first 5 speed auto trans offered for sale in the world and therefore were a bit of an experiment. In the case of my 300CE-24 it was the cam angle sensor that was bad. Hope this helps.

 

[Lewis 2.3 16]

There is an electrical switch that plays up outside of the box by the shifter that will stop a 722.503 from engaging 5th.

I think I may have one, do you have an email address, file size is too large to post here.

Hi
I will send my email over now

Thanks to all of the above replies, the 4/5 gear switch is definitely functional, the problem is the transmission control module isn’t seeing the vehicle speed signal at pin 16 on the TCM so I wanted to trace this back, any input will be much appreciated.

 

[WDB124066]

I've sent you a mail with the service notes for the 722.5 trans in all its iterations. In there is the diagram you are looking for...

Sometimes people have found and succsessfully re-soldered dry solder joints in 124 control modules. Cracked or dry joints are reasonably common. There is a control module test and repair facility in the UK that has served people well on here in the past...

 

[WDB124066]

Vehicle speed signal (output rpm) The output rpm determines when an upshift takes place and thus the shift sequence. It is also detected whether the vehicle is accelerating or decelerating.

According to this it seems the speed signal maybe from RPM, not a wheel sensor...??

CPS could be the culprit if so?

 

[WDB124066]

Shift points, they start normally in 2nd so counting up will have you thinking you are in 4th.

 

[Lewis 2.3 16]

Hi, thanks received the email but it’s a document I have already seen, it’s helpful but not helpful enough, the last 3 pages do contain wiring diagrams but if you look at the bottom of each one is a figure reference the diagrams are for a r129, a w140 chassis so none are applicable to the chassis in question w124 1991 300-24TE. If it’s okay I am gonna see if your friend from car clinic might be able to shed some light.

Oh, An vehicle speed is definitely done on the right fronts hall sensor the value is alternating 3v, it’s not done no other way, well that’s the case in this chassis.

 

[WDB124066]

Where are you measuring.

 

[grober]

https://mercedes-bulgaria.com/Downl...ion Control-ETC/Model 129 with CFI, 722.5.pdf
VSS VEHICLE SPEED SENSOR PIN 16 appears to come from the same source as the electronic speedometer.

 

[kutenets]

Hit a bit of a brick wall trouble shooting a W124 300TE-24v which doesn’t shift into .5th gear, it’s 722.5 transmission (electronically controlled 5th gear/OD). I am getting 6 and 9 blinks on the LED fault read out. According to WIS right front wheel speed sensor is responsible for 5th gear, if a signal speed is seen at 80kmh or more the trans will shift into 5th I’m getting a 3v alternating pulse at right front wheel speed sensor but nothing at the transmission control module.

I am asking if anyone can help in sharing a wiring diagram for the transmission control module and the ABS control module on a w124 300-24v equipped with 722.5 transmission.

Any help will be much appreciated

Hi,

Have you figured out with this issue? I'm getting 6 blinks also.

 

[optimusprime]

car-diagrams.jimdofree.com

 

[optimusprime]

All diagrams in above post ,,sorry you will have to search for them no easy way out .