rl 129 speedo not working

[madbonky]

Hi all,

I have replaced my instrument cluster on my 1991 300sl which was not working with another which i have been assured works, everything does except the speedo, my old cluster has been partially repaired by BBA since, they managed to fix everything except the fuel gauge, when i re-install that cluster the speedo still is not working, they assure me it works on their test bench, just the fuel gauge didnt.

Am i right in beliving the speed sensor could be faulty? I think its fitted to the either n/s or o/s front hub, has anyone any ideas?

Hope you can help!

Jay

 

[television]

Is the cruise control working

 

[madbonky]

Malcolm,

No cruise fitted, ABS light come on and goes off ok......

 

[television]

If thee ABS is working its doubtful that its a speed sensor,,I will see what I can find

Your car should be a 129060

 

[madbonky]

Malcolm,


Someone has mentioned that it could be a small plastic gear in the speedo drive, appartently a common fault, ever heard of this? Do you know where they mean in the speedo drive either?

Jay

 

[television]

If the radio has been changed this can kill the speedo, if not changed remove the plug A from the radio and try it.

The speed signal is taken from the ABS or ABS/ASR unit to drive the speedo thats the N30 or N30/1

Your other cluster,,if it has a digital temp display the gauges can be activared within the cluster or there could be a cap gone on the cluster PCB.

The speed signal for all this is from the LH front but the ABS is already using this

 

[television]

Malcolm,


Someone has mentioned that it could be a small plastic gear in the speedo drive, appartently a common fault, ever heard of this? Do you know where they mean in the speedo drive either?

Jay

Early speedo's were cable driven yours is electronic as I understand it

 

[madbonky]

Malcolm,

My original cluster was the analogue type, the 2 electronic plug type, the replacement one is the type with the digital odometer but the same connections at the back, i understand that there is the 1-9 check you can sometimes do, i will check if it has a digital tepm display.

Jay

 

[television]

I can send you the 1-9 check

 

[madbonky]

Malcolm,

I done the 1-9 check this afternoon, all checked out ok, the speedo went all the way round ok, all the other gauges checked out ok as well. Funnily enough, the mpg gauge doesnt work normally but worked on the 1-9 check but obviously its the speedo im most concerned about. As the speedo worked fine on the check i guess the cluster itself is ok?

Jay

 

[television]

Hello Jay,, the speed signal then does come from the ABS pump as I said earlier, this cant be much but a bad connection can be hard to find,, if you want more info I will see what there is

 

[madbonky]

thanks malcolm, look forward to hearing from you.

jay:bannana: