Can anyone give advise on preliminary troubleshooting the cruise control?

1.Open the fuse box(Driver's side,rear of engine compartment) Take out all the
Old Fuses (Grey Metallic contacts,Aluminum) and replace with new fuses
CERAMIC with copper contacts...clean the "Horns" that hold the fuse ends
before re-installing the new fuses.
Older Aluminum fuses develop microscopic cracks that raise resistance,AND
you never know until you put a multimeter on them to check for continuity.
They also corrode and "Funk UP" the "Horns,further disabling electrical
conductivity.

Report Back

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'84 300SD sold
124.128

I will try that soon. And report back to you.
Thanks

This is PD's user friendly version of service manual.

http://www.pauldrayton.com/uploadfiles/merc/Service/W123/Index/617Tindex.htm

AND wiring diagram of cruise: (it's page 111)

http://www.pauldrayton.com/uploadfiles/merc/Service/W123/w123CD2/Program/ETM/83_300.pdf

All of Mercedes cruise controls are very sensitive to resistance values from the
brake light bulbs (Osram) and they have to be the correct wattage also.(With
one bad bulb...or a funny filament that throws the resistance value off..No
Cruise.) The brake light switch (on the brake pedal lever) if bad will deny cruise.

There is a cruise amplifier (the Brain) and an actuator ( the motor) either of
which can Go South on you.Or the mulitfunction switch on the steering
column can be bad.

O.K. I finally found it! This is the link to General Development Labs
troubleshooting tips for cruise (they rebuild the units):

http://gdl-online.com/testproc.html

That will probably be much more help than my ramblings!

__________________
'84 300SD sold
124.128

Where can you buy the ceramic fuses? I can only ever find the stupid plastic ones.

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1979 240D- 316K miles - VGT Turbo, Intercooler, Stick Shift, Many Other Mods - Daily Driver

1982 300SD - 232K miles - Wife's Daily Driver

1986 560SL - Wife's red speed machine

I am fairly certain that the brake light bulb warning has been proven to be false.
my cruise works with the bulbs out of the car.

__________________
John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!

VSTech,
Does the cruise cancel out when you touch the brakes?

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1981 300TD "The Green Lantern"
1980 300TD
1983 300D Euro "China Cat"

Online. Phil has them as does ********az.

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RRGrassi


70's Southern Pacific #5608 Fairmont A-4 MOW car

13 VW JSW 2.0 TDI 193K, Tuned with DPF and EGR Delete.

91 W124 300D Turbo replaced, Pressure W/G actuator installed. 210K

90 Dodge D250 5.9 Cummins/5 speed. 400K

I should clearify myself. Sorry. The cruise control doesn't work at all!

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1982 300D (W123) 375,000+

Hi
Do you know where I can find the wiring diagram for the instument cluster? It say in the index of http://www.pauldrayton.com/uploadfil...ETM/83_300.pdf
That it is the next index. I can't find it.

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1982 300D (W123) 375,000+

Also what is the correct wattage for the brake light bulbs you mentioned?

It for a 1982 300d chassis W123
Thank you

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1982 300D (W123) 375,000+

Sylvania/Osram doesn't list a '82or'83 300D so we'll go with the 240D which is
another W123 Chassis:
http://www.sylvania.com/ConsumerProducts/AutomotiveLighting/LampReplacementGuide/AutoLRG-Results.htm

You'll have to ask Pdrayton about the "Next Index" missing...

'Talk about serendipity,I just got off the landline with GDL...There is no truth
to the Old Wives/husbands tales about Brake Light bulb wattage,resistance,
Etc.,Etc., affecting the Cruise Control.As long as there is a bulb,incandescent
in the socket the cruise will work.

__________________
'84 300SD sold
124.128