Mystery Cable

[pablo2696]

Hello all

I was checking the ballast resistor for the auxiliary fans when I saw a loose cable wrapped around electrical tape. I removed it and it has three plugs and its probably missing the connector housing.

Cable goes through the ABS/ASR pump and the EZL and it goes down the A/C compressor area... Any ideas what is the purpose of this cable and where should it be connected to?

 

[gsxr]

Can you trace the other end to see where it disappears to inside the fuse box?

Does your AC compressor work, and does the ambient temp display in the instrument cluster work? Kinda looks like the wire to the temp sensor but that shouldn't route towards the AC compressor.

 

[gerryvz]

The A/C compressor electrical connection is a three-prong plug, FYI. You should be able to see the "L"-shaped plastic connector on the top of the compressor with a flashlight, if it is plugged into the compressor.

 

[pablo2696]

Hello Dave/Gerry

Sorry I didn´t reply before... The A/C compressor is working and AC is cold. Today I was finally able to track the cable down and it comes from something that looks like a position sensor


What is this sensor and where should the cable connect to? This sensor looks important and I don´t know why it is not connected...

UPDATE: I believe this is the crank position sensor (or TDC Sender/Sensor... PN: 0021531328 ...?) because of the location and the size of the 3 plugs at the end of the cable. Where should it be connected? I read that starting 93 MB removed this sensor from the M119 engines.

 

[gsxr]

The front crank sensor was for diagnostic purposes only. It was meant to connect to workshop troubleshooting equipment. It isn't needed for the engine operation, and can be removed if desired. As of 1994 USA model year it was deleted, along with the related connector, for cost savings.

 

[Jlaa]

The front crank sensor was for diagnostic purposes only. It was meant to connect to workshop troubleshooting equipment. It isn't needed for the engine operation, and can be removed if desired. As of 1994 USA model year it was deleted, along with the related connector, for cost savings.

Thanks @gsxr. Have you ever used this on any of your prefacelift cars to troubleshoot?

 

[gsxr]

Thanks @gsxr. Have you ever used this on any of your prefacelift cars to troubleshoot?

Nope. I don't have the equipment to connect to it. For most troubleshooting, the live data from HHT-Win is adequate. @Klink or @jhodg5ck might be able to elaborate as to when/why we'd need the vestigial diagnostic connector.

 

[Klink]

Nope. I don't have the equipment to connect to it. For most troubleshooting, the live data from HHT-Win is adequate. @Klink or @jhodg5ck might be able to elaborate as to when/why we'd need the vestigial diagnostic connector.

On MB dedicated diagnostic equipment back in the day one could plug onto that round so-called “diagnostic socket“ and see some various voltage readings, etc. One nice thing that the sensor on the front crankshaft enabled was a live digital reading of the ignition timing. A MB dedicated Sun branded scope for example would show the ignition timing at any given instant on the screen along with a bunch of other basic data like RPM, dwell, etc. That sensor supplied the reference pulse that the diagnostic machine used to calculate the ignition timing which it would show in plus or minus degrees just as it appeared on the crankshaft. Obviously, this was much more useful back when the engines had breaker points, adjustable ignition timing, etc.

 

[sheward]

I haven't heard points mentioned in some time. It was so much easier to tune things up "back in the day" Thanks for chiming in.

I trust you will let us know when any new info comes to light regarding gain of malfunction!

 

[nocfn]

Best points forward

 

[TerryA]

@Klink, Nice to hear from you once in a while. You must be a busy guy.

Take Care