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1980 380SL
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65 Posts
Discussion Starter #1
Just bought this very nice 380SL of 1980 vintage, however, it has a few issues one of which is a non working speedo.
The speedo doesn't work at all, so I'm guessing probably the cable, trouble is having done a little research it seems I could have 2 cables with the speed sensor for the cruise control in between or the cruise control speed sensor could be on the back of the speedo and only 1 cable from the auto box to the speedo.
Anybody know which type I should have and can anyone suggest a UK source for a replacement cable/cables?
 

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Outstanding Contributor , Bob's Your Uncle!
-----'83 280 SL----- 5 speed....The PIG
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29,164 Posts
Just bought this very nice 380SL of 1980 vintage, however, it has a few issues one of which is a non working speedo.
The speedo doesn't work at all, so I'm guessing probably the cable, trouble is having done a little research it seems I could have 2 cables with the speed sensor for the cruise control in between or the cruise control speed sensor could be on the back of the speedo and only 1 cable from the auto box to the speedo.
Anybody know which type I should have and can anyone suggest a UK source for a replacement cable/cables?
I didn't know MB produced a 380SL in 1980.

And at that point of production, I thought the speedo was electric?
 

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Registered
1980 380SL
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65 Posts
Discussion Starter #4
Just checked and mine was UK registered on 29 Sept 1980 and I'm fairly certain the change to electronic speedos took place around 1985 so I think I'm looking for a cable/cables, when I get back home in a few weeks time hopefully it'll have stopped raining and freezing by then and I can have a proper look.
 

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82 380SL 96 SL500 03 SL500
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6,154 Posts
My '82 is electric, and I believe it started at least with the introduction of the 380sl.
 

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R/C107 Moderator
1986 560SL: '84 500SL: '84 280SL 5 speed: other 107s
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31,776 Posts
I have an '81 280SL. It is electronic. I think that is the first model year for the electric.
A 380SL built in 9/80 would be titled as a 1981 model year here because of the MSO provided by MB. Some countries registered the model year as the first sale date.
 

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Outstanding Contributor , Bob's Your Uncle!
-----'83 280 SL----- 5 speed....The PIG
Joined
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29,164 Posts
Just checked and mine was UK registered on 29 Sept 1980 and I'm fairly certain the change to electronic speedos took place around 1985 so I think I'm looking for a cable/cables, when I get back home in a few weeks time hopefully it'll have stopped raining and freezing by then and I can have a proper look.
Sounds like it is an '81 ......and my Euro 83 is electronic.

I doubt you have a speedo cable.
 

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Registered
1980 380SL
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65 Posts
Discussion Starter #9
If it turns out to be electronic when I get home in March what should I be looking for? Is it likely to be the sender unit at the autobox, this failed on an XJS I had a while back and was a quick one out one in job?
All input gladly received between now and then.
 

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Outstanding Contributor , Bob's Your Uncle!
-----'83 280 SL----- 5 speed....The PIG
Joined
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29,164 Posts
If it turns out to be electronic when I get home in March what should I be looking for? Is it likely to be the sender unit at the autobox, this failed on an XJS I had a while back and was a quick one out one in job?
All input gladly received between now and then.
All the other gauges work properly?
 

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Registered
1980 380SL
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65 Posts
Discussion Starter #13
OK I'm back home now and have been poking about underneath and can't find anything that looks like a cable speedo drive so am beginning to think it must be electric so where exactly on the gearbox will I find the speed sensor?
Just to be sure if it were a cable drive where would that be?
Please help as my wife has kittens every time we see a police car!!!
 

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Registered
1980 380SL
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65 Posts
Discussion Starter #14
Quick update, just been to my friend in the trade and put the old girl up on the lift and as far as we can tell the speed sensor is on the left rear of the gearbox i.e. passenger side in my case(rh drive).
Not very accessible due to the shields under the gearbox, anybody know of any way to test it other than by substitution for a known good one?
Next job is to pop out the instruments to check the plug hasn't come out of the back and replace all the lights that are off at the same time.
I'll be back as things develop.
 

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Registered
1980 380SL
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65 Posts
Discussion Starter #15
Further update, still not got a working speedo, have had it out so much checking different things I just have to whistle and it jumps out onto my lap!!
It appears that someone has been in here before (missing/stripped screws) but the good news is the odo gears are all good!
Tested for power at the lead to the speedo yesterday and with ignition on I get 4.7volts which goes off when I switch off the ignition so I guess the circuit is sound, but don't know if this voltage is correct?
Didn't try moving, the car as I didn't have a steering wheel, to see if the voltage pulsed, anyone know if this voltage is normal?
Am looking at getting another speedo to try but if this still doesn't work that's money down the drain so would like some more info before I go down that route.
Please help!
 

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Registered
1980 380SL
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65 Posts
Discussion Starter #16
Found a company called Speedycables not too far from me who say they can check my speedo and repair as required so I'm taking it to them tomorrow.
In the course of my research I thought I'd check out VDO on the interweb and came across a link to a Porsche forum where I found lots of usefull info on the similar electronic speedos fitted to their cars.
It appears that the IC on the small PCB on the back of the instrument is a frequent source of trouble, their's use a UAF2115 whilst mine is a UAF0115 both made by ITT, there is also discussion about changing to a LM2917 which apparently has some advantages which I don't fully understand, as me and electronics have never got on with each other, but needs a reworked circuit to work properly.
I'll let you know how I get on tomorrow, meanwhile if there are any electronic whizz kids out there the above might be of interest.
 

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1980 380SL
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65 Posts
Discussion Starter #17
At last I've got a working speedo, took it to Speedycables, about 12 miles north of Swansea, and they fixed it for me on the spot! Cost was £96 but as I was quoted £120 for a second hand one I would say that's a result and that includes 12 mth warrantee on the repair.
Their web site is Car Cable manufacturer, Speedometer, Tachometer, Rev Counter, Clock and Gauge Repair, Sales and Restoration and they do a postal service as well, the guy who fixed mine was telling me they had new parts for these instruments which they've gathered over the years.
Well worth a call if you need anything at all to do with instruments.
 

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Registered
1980 380SL
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65 Posts
Discussion Starter #18
At last I've got a working speedo, took it to Speedycables, about 12 miles north of Swansea, and they fixed it for me on the spot! Cost was £96 but as I was quoted £120 for a second hand one I would say that's a result and that includes 12 mth warrantee on the repair.
Their web site is Car Cable manufacturer, Speedometer, Tachometer, Rev Counter, Clock and Gauge Repair, Sales and Restoration and they do a postal service as well, the guy who fixed mine was telling me they had new parts for these instruments which they've gathered over the years.
Well worth a call if you need anything at all to do with instruments.
BTW it was the IC which had failed, also one of the capacitors had gone so he changed both of them.
 
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