Where do these wires connect to? - PeachParts Mercedes-Benz Forum

ericnguyen · #1 04-22-2003, 09:21 PM

Dear friends:

I bought an old 240D where lots of stuff got messed up or disconnected in the engine compartment. Please help me
track down where the marked wires in the attached image should be connected to.

Thanks a lot.

Eric

JimSmith · #2 04-22-2003, 11:41 PM

Eric,

If this is the thread you asked about, I have no idea what this is. If my 240D was in the driveway, I would go out and look, but it is not (my daughter takes it to college) so I cannot be of much help. I am sorry to leave you high and dry. Good luck, I am sure someone will respond with a definite identification. Jim

#3 04-23-2003, 12:29 AM

Can you take a few more pictures of the engine?

westkill · #4 04-23-2003, 07:30 AM

generally, wires that are unshielded and have ring terminals at the ends are grounds. They most likely bolt to the engine possible utilizing a valve cover bolt. If they are long enough to reach the firewall, look to see if there is evidence of a screw/bolt missing. THey can cause guages to read erratic or not at all. HTH.. MIke

ericnguyen · #5 04-23-2003, 05:57 PM

Dear friends:

I will try to take some more pictures tomorrow. Meanwhile,
I wonder whether LarryBible can take a look at his 240D engine
compartment and see whether there's any similarity between
his and mine.

westkill: the other ends of these 2 wires are already connected to the engine block, so I believe the open ends must be connected to something else. Unfortunately, I could not find anything near them on which there's evidence of a screw/bolt missing.

Best regards,

Eric

ericnguyen · #6 04-23-2003, 06:26 PM

Dear friends:

On my 1981 240D, I saw 2 strange plugs which are connected
to the same engine side (right facing the front of the engine) as
the 4 glow plugs. You can see them clearly as 1 and 2 on the attached image. What are these 2 strange plugs and what are their function?

BTW, the plug #1 has an attached connector while the plug #2
doesn't have anything. Am I missing some connector here?

Thanks a lot for your help.

Best regards,

Eric

#7 04-23-2003, 06:37 PM

Number 2 looks like the temp gauge sending unit.

#8 04-23-2003, 06:48 PM

Yes, #2 does look like the temp sending unit. Let me take a picture of my engine, and maybe we can figure something out, even though I don't have a 240D...

ericnguyen · #9 04-23-2003, 07:06 PM

Dear Old Deis and 123c:

If #2 is the temperature sending unit, there must be some connector attached to its tip. Am I right?

The #2 shown in my attached image does not have any connector
attached to it.

Thanks.

Eric

JimSmith · #10 04-23-2003, 07:10 PM

Eric,

That connector must either be gone (like your connector for the cruise control speed signal), or dangling somewhere on the driver's side of the engine compartment. Jim

#11 04-23-2003, 07:12 PM

I guess the first question to ask is does your temp guage seem to read correct?

ericnguyen · #12 04-23-2003, 07:18 PM

Dear Mr. JimSmith:

According to M.B.DOC, the connector for the cruise control speed signal is actually for the crankshaft pick-up unit, which is not available on most 240D's. It's only used for special equipments to perform crankshaft speed comparisons or for 240D's which are
equipped with a tachometer. So my car may actually be missing nothing for that connector.

Best regards,

Eric

JimSmith · #13 04-23-2003, 08:13 PM

Eric,

Once again if my 240D was here I would check it to make sure, but the car is not available. However, there are a number of different cruise control systems used on 240D's, from model year to model year, or even within model years. For example, none of the throttle linkage hardware connecting to the cruise control, or the actuator, is the same on my father in law's 1980 240D.

I am reasonably certain the sensor at the crank is the cruise speed signal because on my car I pressure washed the engine and blew that little sensor off its mount, and the cruise system stopped working. Since it was the only thing that stopped working, I was pretty sure it was the cruise speed input signal.

240D's to my knowledge did not have tachs, and Diesel tachs on 300D's are driven by a signal from part of the drive to the oil pump. I cannot imagine what the sensor at the crank is for if not to measure crank speed, and on a 240D from this era, there is not much to do with an electrical signal of crank speed, other than use it for cruise control. Good luck figuring this nest of loose wires out.

Jim

ericnguyen · #14 04-23-2003, 11:12 PM

Dear Mr. JimSmith:

I believe your information is accurate, because it makes no sense if the crankshaft speed pick-up connector was left dangling in the engine compartment without connecting it to any particular device.

If you have a chance to work on your 240D in the future, please take a pic of the area where it shows the device to which the cruise control signal connector is connected. On my car, the only device that's close to this connector is the cruise control actuator.
However, I do not see any part around the actuator that allows me to attach the cruise control signal connector.

Thank you very much.

Best regards,

Eric