Outside Temperature Gauge ... - Mercedes-Benz Forum
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#1 (permalink) Old 06-25-2013, 12:24 PM
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Outside Temperature Gauge ...

The Outside Temperature Gauge in my recently acquired 560SL
does not work. I looked under the front license plate for
a temperature sensor but could not find it or evidence of wiring.

How is this done in a 560SL?
Any hints about locating the wiring as it routes under the hood?

Carl

PS as much sorting as I'm having to do with this 560SL, I've
been learning a lot:-) Thank goodness my 380SL is basically
problem free.

Carl



"You have chosen to drive a MERCEDES-BENZ, a car in whose construction and production we have taken great pains because we believe that quality is not a matter of chance." -- page 3, Owners Manual 380SL
Timing Chain, Subframe, wiring harness, Climate Control, Rust prevention, etc.
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#2 (permalink) Old 06-25-2013, 12:40 PM
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Quote:
Originally Posted by cwmoser View Post
The Outside Temperature Gauge in my recently acquired 560SL
does not work. I looked under the front license plate for
a temperature sensor but could not find it or evidence of wiring.
That's where its suposed to be, page 201, figure No. 2 in the manual (electrical troubleshooting, component location). Picture in manual is crap, btw...

Quote:
How is this done in a 560SL?
Only diff I see from 380 is the gauge is in F, not C...

Quote:
Any hints about locating the wiring as it routes under the hood?
maybe look at 380 for an idea?

Quote:
Carl

PS as much sorting as I'm having to do with this 560SL, I've
been learning a lot:-) Thank goodness my 380SL is basically
problem free.
Hang in there...

RM Smith www.rmsmithco.com

Where is it again that we are going... And why are we in a handbasket?

Last edited by Ears; 06-25-2013 at 12:42 PM.
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#3 (permalink) Old 06-25-2013, 01:17 PM
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temp sensor wire routing

Carl,

Best I can tell on my '88, the wire runs from directly behind the license plate bracket, thru the lower grills (center of grill), up to and along side the cross-bracing, thru the bulkhead on the passenger side (and enters a loom), then along the passenger side to the firewall. I lost it there, if I was following the correct wire

RM Smith www.rmsmithco.com

Where is it again that we are going... And why are we in a handbasket?

Last edited by Ears; 06-25-2013 at 01:20 PM.
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#4 (permalink) Old 06-25-2013, 02:08 PM
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Quote:
Originally Posted by Ears View Post
Carl,

Best I can tell on my '88, the wire runs from directly behind the license plate bracket, thru the lower grills (center of grill), up to and along side the cross-bracing, thru the bulkhead on the passenger side (and enters a loom), then along the passenger side to the firewall. I lost it there, if I was following the correct wire

Thanks Ears. With your guidance I found the Outside Temp Gauge wire.
Apparently the PO sh*t-canned the Thermistor behind the License Bracket
as none was there. In addition, the PO taped off and tucked the wire behind
the right headlamp.

I installed a 4.7K ohm resistor to see if that was the wire and indeed the
Temp gauge came to life.

Thanks. Now I have to find a suitable Thermistor ... or, maybe I can put
this to a more useful purpose like say monitor the temperator at the Radiator.
Hmmm

BTW, I did not leave the wires open -- soldered and put on heat shrink.
So at least I have a Temp Gauge that looks like it is somewhat working:-)
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Carl



"You have chosen to drive a MERCEDES-BENZ, a car in whose construction and production we have taken great pains because we believe that quality is not a matter of chance." -- page 3, Owners Manual 380SL
Timing Chain, Subframe, wiring harness, Climate Control, Rust prevention, etc.

Last edited by cwmoser; 06-25-2013 at 02:14 PM.
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#5 (permalink) Old 06-25-2013, 03:17 PM
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I was never able to come up with a thermistor with exactly the curve of the real part - this MB part is very expensive, and THEN you have to route the wiring. I obtained one from a junked car and spliced it it to the remaining wiring (shrink tubing hopefully waterproofed it).

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#6 (permalink) Old 06-25-2013, 04:03 PM
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Originally Posted by strife2 View Post
I was never able to come up with a thermistor with exactly the curve of the real part - this MB part is very expensive, and THEN you have to route the wiring. I obtained one from a junked car and spliced it it to the remaining wiring (shrink tubing hopefully waterproofed it).
Do you have a resistance to temperature curve chart for the Mercedes Thermistor?
Better yet, it would be nice to know the part number of the Thermistor used.

Carl

Carl



"You have chosen to drive a MERCEDES-BENZ, a car in whose construction and production we have taken great pains because we believe that quality is not a matter of chance." -- page 3, Owners Manual 380SL
Timing Chain, Subframe, wiring harness, Climate Control, Rust prevention, etc.
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#7 (permalink) Old 06-25-2013, 05:16 PM
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My '91 126 has the same temp gauge I think. The readout screen ends up in that rectangular blank (on my 380) in the instrument cluster. Mine was all one piece when I replaced it for $180 ! I figured it wasn't worth the money to put one in the 380, but at the time I was doing a lot of country driving in the 126 with temps ranging from zero to 30C on the same day.
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#8 (permalink) Old 06-25-2013, 05:30 PM
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Quote:
Originally Posted by cwmoser View Post
Do you have a resistance to temperature curve chart for the Mercedes Thermistor?
Better yet, it would be nice to know the part number of the Thermistor used.

Carl
A001 542 26 18
You rang... (can't believe I beat Rowdie to this...)
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Where is it again that we are going... And why are we in a handbasket?
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#9 (permalink) Old 06-26-2013, 04:15 PM
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Put in a multi position switch and several thermistors and check temperatures all around the car. Or maybe an electronic scanning circuit that just keeps going around one by one.

Craig S
1973 450SL
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#10 (permalink) Old 06-26-2013, 05:32 PM
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Originally Posted by Ears View Post
A001 542 26 18
You rang... (can't believe I beat Rowdie to this...)
I was going to check the '84 parts car to see if if it is still there. Totally slipped what ever is left of my mind. If it is can the wires just be cut ?
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