'81 300SD-No Cruise Control
 

I replaced the actuator (003 545 86 32) and still no Cruise.
If the Tach doesn't work will this prevent the Cruise from working? (I replaced EVERY bulb in the Tail lights with Jahns bulbs, btw)
I had previously replaced the RPM sensor (001 545 59 32) with no help in the tach working.
Now, mind you, I do work for a guy who's a GREAT Benz mechanic (26 years with them) but there's only so much help I can pester him for. We're so swamped with PAYING jobs (had to hire another mechanic just to keep up with the load) that I can't bring myself to burden him with trouble shooting THIS, on the car he advised me not to buy-the300SD, anyway.

I run this shop-save most of the actual wrenching- andI get all my car parts at shop cost-not just a discount (saved THOUSANDS...so far in new parts getting this to where I'd like it, if I were just a guy off the streets) so I try not to push the envelope.;)

Appreciate any tips or thoughts.

BTW, if there are any guys out there without parts connections, in the S.F. area, email me and I'll see if I can help.

Thanks,
FJ

I'm not familiar with your model of car, but try doing a search for cruise control amplifier on this forum. It seems to be the leading cause of a nonworking cruise control in these cars.

Btw, did you mean SF Bay Area? Pretty sure you didn't mean gay area...

*** Something I noticed... ***
 

I found this to be more of a proceedural issue than mechanical...

I've got a 280E ('77) and IF I don't have the doors locked (vaccuum system) the cruise doesn't work...

Lock the doors? Cruise holds beautifully...

Don't lock the doors? Cruise won't engage, set and operate...

Must be something about the Germans' logic of "You're not going to operate this machine, in a "relaxed state of mind" if you haven't performed a simple, but effective, safety function first..."

Try locking the doors then engage the system...VERY cheap test...

GL!

You've got a vacuum actuator for the '77. He's got an electric actuator. The doors won't make any difference.

Wow...now THAT'S a good one...
 

especially since the vacuum locks on the doors are crappy, too.

And that's a 'test' I can do the next time I drive!

Thanks mg!

FJ

Ooops...
 

Thanks Brian-makes sense.
But in the interest of 'science', I'll try mg's thought, anyway.
;)

FJ

So, Brian...
 

might I ask YOUR suspicions and suggestions?

FJ.

I'm hesitant to reply because I cannot recall if the tach is required for the cruise.........so, no point in going any further until we get that resolved.

I don't believe that they are related on the SD, but am not positive.

You can do a pretty good test of the actuator using this site:

http://www.fix.net/~gdl/test023.html

If the actuator checks out OK..........you've confirmed that the amplifier is the culprit.........and it's time to shell out $200. or so.

Thanks Brian...
 

I'll copy the test and slip it on to the mechanics desk for his perusal.
He's a fargin' whiz at trouble shooting and with this info it should really aide him.

THANKS!:D

I'll let you know how it turns out, God willing we get some free time, next week.

My cruise isn't working either in my '83 300SD. I tried to do the test you linked to, but when I pulled the cover off the actuator plug to do the amperage test between pins 4 and 5, both sockets were empty. What does that mean?

WTF is with all the anti-gay comments?

Deleted.