Want to install economy gauge on my 91 w124 - PeachParts Mercedes-Benz Forum

JordaanDMC-12 · #6 01-13-2013, 02:13 PM

Quote:

Originally Posted by JimFreeh

I thought about doing this a long time ago....

My recollection, admittedly fuzzy, is that the wiring (printed circuit and round pin connector) was not consistent in all W124 instrument panels.

Wasn't worth the effort for a gauge that only told me when I was on the throttle...

There are oddball things the aux cluster manages, for instance, the delay circuit for the low oil level float resides there.

Jim

That's exactly right! As I learned the hard way yesterday! I got another gauge yesterday and put it on, worked great all was well, until I notcied the instrument, window switch lights were not coming on. I figured the little red fuse must be bad so I checked it and low and behold there wasn't one!!!! I was already back home and 30 miles away from the junkyard when I figured this out. So I was not about to drive back once again to get a different one. What I ended up doing was unscrewing the actual instruments without removing the needles and putting it on the circuit board that had the red fuse. Thankfully, you can swap them from one board to the other as all circuit boards have the hole for the eco gauge. So I was finally able to finish. I now have a working eco gauge!

So if anyone is about to attempt this, this is what I advise, it's easy, but can be tedious.

SAVE your working instrument gauge circuit board! (Just in case)

Go to the junkyard and find a gauge and take the vacuum hoses from the doner car. (I'd post pictures, but once you're at the yard, it pretty self explanatory)

If all you could find was a board that doesn't have that red twist off fuse, you're going to have to swap boards or else you won't get any dash lights.

If you have to swap, just unscrew the instruments from the back, you'll see the gold nut that holds them and then slowly and carefully pry up on them until they pop off (No unscrewing of the faceplate is necessary, it all comes off in one piece!)

Once it's off, just put it on the new board as it was on the old one and you're good to go!

I found it was best to feed the vacuum hose through the front of the car rather than from inside (connects to manifold near the transmission bowden cable) poke it through the rubber where you see two other vacuum hoses going and feed it through until you catch it behind the instrument cluster and connect it to the board and you should have a fully functional economy gauge.