Junction box on inner fender for checking starter? - PeachParts Mercedes-Benz Forum

retx · #1 01-31-2008, 06:31 PM

Ive looked through the fsm and cant seem to find any mention of it. Ive read on other posts that its on the right (passenger) fenderwell. I cant seem to find one over there at all. Im still having issues with getting the starter to engage. Currently, nothing, not a thing, happens when the key is turned fully. First postion of the key gives me all dash lights and glow, but nothing when turned to postion two. Headlights dont dim much, lights inside stay bright when i attempt to crank it.
So in trying to rule out a bad starter, im looking for this junction box. Do some models have them on the left (drivers) side? i have one there just behind the washer tank.

kerry · #2 01-31-2008, 06:52 PM

Never heard of one on the left fender. Some 123's don't have the junction box.

retx · #3 01-31-2008, 09:38 PM

Ah, so some dont have them at all. Does anyone have a pic of the box, just so i have a visual?
And what would that box be on the drivers side? A multiconnector in there, and three screw connectors, two are jumped together and one on the lower right corner.

toomany MBZ · #4 01-31-2008, 11:29 PM

If you don't have a junction box, very close, and just in front of, the battery, you'll need to use the start screws, check pic.
With a junction box, I use the first and third screw, trial and error, works.

retx · #5 02-01-2008, 05:44 PM

Interesting, i guess my car doesnt have the junction box at all, nor does it have the two screws toomany is referring to (unless youre meaning the two on the solenoid).
This is the closest box i could find with exposed screws. On the left side though, behind washer bottle. Cant find anything in the fsm about what this is.

kerry · #6 02-01-2008, 05:48 PM

Glow plug relay. That's the 80amp glow plug fuse visible in that box.

retx · #7 02-01-2008, 05:55 PM

ah. ok. are they all supposed to be 80a? this one has 60a printed on the side.
thanks for clearing that up though.

vstech · #8 02-01-2008, 05:56 PM

the 80 123 should have the box on the frame down low, not on any fender. on the passenger's side. easiest way to find it is to follow the wire from the alternator. it goes right to it.

kerry · #9 02-01-2008, 06:10 PM

Quote:

Originally Posted by vstech

the 80 123 should have the box on the frame down low, not on any fender. on the passenger's side. easiest way to find it is to follow the wire from the alternator. it goes right to it.

That little nugget of information helped me find the junction box for the W116 under the battery tray. It's hard to see and it wouldn't be easy to jump the terminals there and I can't tell if it has three terminals or two. Anyone know if the SD is jumpable at the terminal block under the battery tray? If so which terminals need to be jumped?

junqueyardjim · #10 02-01-2008, 06:24 PM

Take a needle nose plier and touch two of the terminals. Switch does not have to be on unless you are trying to start it. If touching two terminals doesn't produce results, try the other set up. You might see a few sparks, but they are harmless. Might even make you jump if you were not expecting it. You have to put that needle nose into the screws pretty good if you want to crank it up. Just touch briefly if you want to move the engine when doing a valve adjustment.

retx · #11 02-01-2008, 06:30 PM

Following the wiring from the altenator leads me under the battery tray, which i then removed, but they just disappear into an opening. No terminal block or junction box. I was finally able to locate a screwdriver long enough to make it all the way down past the manifold to reach the solenoid. Starter does turn over at normal speed. So its not the starter, new battery or new cables/ends. In the daylight tomorrow ill crawl under to see if the ground strap is fubar'd. On the 123 where "should" it be?

kerry · #12 02-01-2008, 06:31 PM

It's awkward to reach. Probably would have to remove the air cleaner to turbo plastic U thingamajob in order to jump the terminals, so I was wondering if anyone else has experimented.

bulletproofair · #13 02-01-2008, 09:18 PM

This "Junction Box" is located on the passenger side fender inside the engine bay. There are 5 screws holding down wires to the starter and the alternator along with the battery and some other acc\power wires I believe. The screws are under the pop up lid and its just a little plastic box that's black.

You can jump the terminal closest to the windshield with the terminal 2nd from the front of the car and it should engage the starter. If its wired different for some reason just look for the wire going to the starter and a wire with power then jump them I think.

If starter doesn't engage then your starter is bad or solenoid is.

Hope this helps and clears things up for everyone. I always encourage accurate information to be spread.

If you don't have everything wired up correctly in this terminal box your car most likely won't turn over\start or some electronics may have problems or not work.

Good Luck.

retx · #14 02-01-2008, 10:04 PM

That box does not exist on my car obviously, as kerry has mentioned. Ive searched the entire bay from the fenderwell to the suspension. It just does not exist. My starter is fine. It has to either be the switch, nss, or ground strap.

charmalu · #15 02-01-2008, 10:19 PM

Quote:

Originally Posted by toomany MBZ

If you don't have a junction box, very close, and just in front of, the battery, you'll need to use the start screws, check pic.
With a junction box, I use the first and third screw, trial and error, works.

On my 85 300D, it`s wired to jump the middle screw and the front one.

If the neutral safety goes bad, you can start the car by jumping here
also.

Charlie