how to get at outside temp sensor cable connector - PeachParts Mercedes-Benz Forum

jsmith · #1 08-14-2002, 10:33 AM

i figured out a while back where the cable ended - under the fuse box. i want to unhook it and clean the terminals as i my display still fades in and out. it seems to act up when it's really humid - that's the only correlation i've found. i already replaced the thermistor. i tried to unhook it once but it's really tight in there and i couldn't get a grip on the snaps. are there any tricks to this? i had unscrewed the top half of my fuse box to get at it - do i need to go farther?

on a somewhat different track - the LCD display fades in and out, sometimes w/ solid numbers, sometimes fading to nothing. early part of the summer it was on solid for a couple of months. this isn't a sign of a broken LCD is it? from previous threads, a broken display would either be solid or partially black...

jsmith · #2 08-15-2002, 01:54 PM

well, that was a dead end. i managed to unhook the cable and tested with a 3k ohm load and it was the same. so it was never the probe/cable after all, wished i had been able to get at the plugs back then (it was winter and cold numb fingers couldn't get a good grip). i guess the problem is at the instrument cluster - gotta figure that one out now. anyone out there have tips for an R&R of the cluster?

Billybob · #3 08-15-2002, 02:20 PM

Do a search under "dpetryk", Dave has a post with a complete step by step including pictures! or you can try insrtument cluster, pulling, hooks, removal and you should be able to find it. He has pics of exactly how the tools work and how they act on the cluster. A couple of screws (up from below) hold the Ambient Temp Module to the bottom of the instrument cluster. Remove the screws and pull the module back and outwards.

You can open up the module and examine the connection between the LCD panel and its driving circuitry, maybe that is the problem? The boneyard is the least expensive source for replacements, the dealer gets around $200 for a new module. You can swap out the circuitry and LCD if you get a used part. Most of the time the LCD is damaged but the electronics are still good so if your LCD display is good you just need a module with a damaged LCD display! Thats the cheapest kind! I have a F display in my 87 SDL and have heard that the only years for F is 86 & 87 SDLs all the rest are C! But I can't confirm that! Good Luck!

P. S. Found this:
How to remove instrument cluster.

Moab_dan · #4 08-15-2002, 02:25 PM

My display was doing the exact same thing but only during and after it had rained. I cut the rubber insulation away from the sensor where the cable enters the metal barrel of the sensor. Worked some permatex into the gap between the cable and metal barrel of the sensor. Wrapped electrical tape around the joint while the permatex was wet.

It has been raining everyday here in florida and since I did the fix I haven't had any problems.

The joint where the cable entered the metal barrel looked tight but I guess enough moisture was getting into it to send the display nuts.

Maybe this helps.

Dan

jsmith · #5 08-15-2002, 03:31 PM

bb,

thanks, i found that thread. i'm hoping it's a loose / dirty connection. if not, then i have to go looking for a used temp mode module.

moab_dan,

i do think it has to do with humidity / temp changes. i have already changed the thermistor and immediately after it was still behaving the same way. it is blank at the moment and i put a 3k load at the connector in the fuse box and it remained blank so i think the cable and probe are not it...