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'88 560SL - 2nd generation "original owner", 17k miles
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Discussion Starter · #1 ·
After unsuccessfully getting my '88 560SL to fire, someone suggested that I remove the two wiring harnesses that plug into the Radio/Alarm ECU that's behind the access panel in the glove compartment. I even took pictures before I removed the 2 harnesses - one came off completely intact, the longer 14-pin connector did not.

I've attached pictures of the ECU, the 14-pin harness, and the wires that need to be plugged into the harness. I've searched Startekinfo, and any other resource without luck.

Any help is appreciated!
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20210412_122710_HDR.jpg
20210412_113102.jpg
20210412_104416.jpg
 

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'88 560SL - 2nd generation "original owner", 17k miles
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Discussion Starter · #2 ·
After unsuccessfully getting my '88 560SL to fire, someone suggested that I remove the two wiring harnesses that plug into the Radio/Alarm ECU that's behind the access panel in the glove compartment. I even took pictures before I removed the 2 harnesses - one came off completely intact, the longer 14-pin connector did not.

I've attached pictures of the ECU, the 14-pin harness, and the wires that need to be plugged into the harness. I've searched Startekinfo, and any other resource without luck.

Any help is appreciated! View attachment 2690590 View attachment 2690591 View attachment 2690592 View attachment 2690590 View attachment 2690591 View attachment 2690592
 

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Discussion Starter · #3 ·
I should note, I've looked everywhere for the pictures I took prior to unplugging this module, not in my cloud drives or even old phones
 

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After unsuccessfully getting my '88 560SL to fire, someone suggested that I remove the two wiring harnesses that plug into the Radio/Alarm ECU that's behind the access panel in the glove compartment. I even took pictures before I removed the 2 harnesses - one came off completely intact, the longer 14-pin connector did not.

I've attached pictures of the ECU, the 14-pin harness, and the wires that need to be plugged into the harness. I've searched Startekinfo, and any other resource without luck.

Any help is appreciated! View attachment 2690590 View attachment 2690591 View attachment 2690592 View attachment 2690590 View attachment 2690591 View attachment 2690592
what do you mean by fire , dont crank , or crank and dont start .it was common to disconnect the alarm on those , so , even if plug came apart , that should not be a problem .i wish that somewhere , someone would open a business , that for a fee would send you the wiring diagram for that plug .i dont want spend crazy time trying to find it in WIS or ???? .wiring diagrams on old old cars was simple , the all car on one sheet of paper , modern cars are nuts .
 

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'88 560SL - 2nd generation "original owner", 17k miles
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Discussion Starter · #5 ·
At the time, it didn't "run" - the starter would just crank, but not "fire" .

That's resolved now, it runs very well, but that black box is the radio and alarm interface .

I'm just looking for what wire color codes correspond to each of the 14 pins shown in the photo.

In other words, solid red goes on pin 2, etc.

Thank you
 

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At the time, it didn't "run" - the starter would just crank, but not "fire" .

That's resolved now, it runs very well, but that black box is the radio and alarm interface .

I'm just looking for what wire color codes correspond to each of the 14 pins shown in the photo.

In other words, solid red goes on pin 2, etc.

Thank you
have you tried plugging in the good plug and leaving the bad one out .one could be just the alarm , and other the radio . if someone has same car , just take picture of the bad plug with back off , so you can see the colors .
 

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Discussion Starter · #7 ·
The 6-7 terminal plug (I think) provides the alarm support. The other side has the typical speaker wire colors - what's strange is that there's only 2 speakers in the car, but the color codes for a total of 4 speakers (8 of the 14 wires) are used. That's more than 50% solved - well, not really, because I don't know which one they connect to. I even called Becker (the maker of the OEM radio and the maker of the radio and alarm ECU. They were less than helpful. I think the guy I was speaking with was younger than my car.

Someone will have the info I'm sure. I've just got to be patient! Thanks!
 

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1973 450 SL
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If you pull that de-pinned connector body out of the alarm module (left side of second picture in post #1), you will find pin bushing numbers embossed in the plastic. Pages 128 and 129 of the 86 thru 88 ETM depict the wiring for both connectors on that alarm module. I think the broken one is depicted on page 129. Match the colors of your dangling leads into the pin bushing locations from the diagram and you should be good to go.

In the attached ETM page 129, focus on the N26 Anti Theft Alarm Control Unit in the middle of the page. The pin numbers are adjacent to the leads. Colors of the leads are depicted.
 

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Discussion Starter · #9 ·
Did not reference the member who supplied the information.
 

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Discussion Starter · #10 ·
If you pull that de-pinned connector body out of the alarm module (left side of second picture in post #1), you will find pin bushing numbers embossed in the plastic. Pages 128 and 129 of the 86 thru 88 ETM depict the wiring for both connectors on that alarm module. I think the broken one is depicted on page 129. Match the colors of your dangling leads into the pin bushing locations from the diagram and you should be good to go.

In the attached ETM page 129, focus on the N26 Anti Theft Alarm Control Unit in the middle of the page. The pin numbers are adjacent to the leads. Colors of the leads are depicted.
If you pull that de-pinned connector body out of the alarm module (left side of second picture in post #1), you will find pin bushing numbers embossed in the plastic. Pages 128 and 129 of the 86 thru 88 ETM depict the wiring for both connectors on that alarm module. I think the broken one is depicted on page 129. Match the colors of your dangling leads into the pin bushing locations from the diagram and you should be good to go.

In the attached ETM page 129, focus on the N26 Anti Theft Alarm Control Unit in the middle of the page. The pin numbers are adjacent to the leads. Colors of the leads are depicted.
cushjbc,

Thank you very much! What I neglected to mention, was that I pulled this harness off in 2017 - and that's the reason I'm having such a hard time locating the original pictures taken.

Thank you for providing these two diagrams - it will take some studying before it makes complete sense to me. I have little experience in reading electrical circuits - but I can see in the center of page 129, it's clearly marked x1 8 pole, x2 14 pole. I plan on studying the wire color and positions for the 8 pole plug - receptacle, and from this, I will be able to apply the same logic to the 14 pole plug - receptacle. I will refer to the beginning of the electrical system manual for color codes/abbreviations.

I'm confused by another issue - I thought the radio outputs run through this some module, yet I don't see any indicators for speaker wiring. Right now, there is an aftermarket radio installed that I installed myself sometime in the early '90s. I used factory/aftermarket wiring adapters to avoid cutting into any portion of the factory harness. I still have the original, working Becker Grand Prix radio stored in the vehicle.

Sincere appreciation,

BR
 

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cushjbc,

Thank you very much! What I neglected to mention, was that I pulled this harness off in 2017 - and that's the reason I'm having such a hard time locating the original pictures taken.

Thank you for providing these two diagrams - it will take some studying before it makes complete sense to me. I have little experience in reading electrical circuits - but I can see in the center of page 129, it's clearly marked x1 8 pole, x2 14 pole. I plan on studying the wire color and positions for the 8 pole plug - receptacle, and from this, I will be able to apply the same logic to the 14 pole plug - receptacle. I will refer to the beginning of the electrical system manual for color codes/abbreviations.

I'm confused by another issue - I thought the radio outputs run through this some module, yet I don't see any indicators for speaker wiring. Right now, there is an aftermarket radio installed that I installed myself sometime in the early '90s. I used factory/aftermarket wiring adapters to avoid cutting into any portion of the factory harness. I still have the original, working Becker Grand Prix radio stored in the vehicle.

Sincere appreciation,

BR
looking at the wiring diagram , only 2 wires feed the radio alarm .what you have here is the alarm module , it also feed the radio alarm thru 2 wires .those radio where a pain , disconnecting the battery would kill them temporarily .some radio repair shop used to eliminate that radio alarm .it seem to me at the time , i used to unplug both plugs to terminate the alarm .it did not seem to affect the radio .on newer cars when the alarm go off as a nuisance , a scanner will tell you what circuit did that , not on older cars .so hard to figure out .
 

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'88 560SL - 2nd generation "original owner", 17k miles
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Discussion Starter · #12 ·
I'm almost there - I think!
I've got a brown/red wire (coming from the same harness with the other pins) that I can't seem to figure out where it goes. I know all 14 pins (in the connector) aren't occupied, but I have this brown/red wire with a pin that I can't seem to ID or find a location for within the 14 pin harness. Any ideas? Is the 1988 MY different in this area?

Thank you
 

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I'm almost there - I think!
I've got a brown/red wire (coming from the same harness with the other pins) that I can't seem to figure out where it goes. I know all 14 pins (in the connector) aren't occupied, but I have this brown/red wire with a pin that I can't seem to ID or find a location for within the 14 pin harness. Any ideas? Is the 1988 MY different in this area?

Thank you
if you have a after market radio , the alarm should have no effect .see if you have power going to the radio .
 

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I have this brown/red wire with a pin that I can't seem to ID
I do not see a brown/red in that section of the ETM. Please confirm it is terminated by a pin (male), not a pin bushing (female) - makes a big difference.

The ETM states "AS OF MY 1986" in the upper right corner which leads the reader to believe there were no changes in that harness up to the end of production. I have seen discrepancies and variation in wiring diagrams and ETMs however. If you can provide a list of what wires you were able to accurately place in which locations, maybe we can solve it by process of elimination. A picture would help as well.
 

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I'm almost there - I think!
I've got a brown/red wire (coming from the same harness with the other pins) that I can't seem to figure out where it goes. I know all 14 pins (in the connector) aren't occupied, but I have this brown/red wire with a pin that I can't seem to ID or find a location for within the 14 pin harness. Any ideas? Is the 1988 MY different in this area?

Thank you
could you answer the question , if you have a after market radio , what does the alarm have to do with that ?? .
 

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Discussion Starter · #16 ·
could you answer the question , if you have a after market radio , what does the alarm have to do with that ?? .
The 8-pin connector supplies power, speaker outputs, antenna trigger and illumination.

The 14-pin connector controls central locking/unlocking, courtesy lights for when each door is open AND provides alarm functions.

What I'm referring to has nothing to do with the Becker Grand Prix's "deactivation feature" that's easily solved by grounding black/blue wire (from memory - I could be wrong)

I have both radios - an aftermarket Blaupunkt and the original Becker Grand Prix that still works. I'm re-installing the Becker Radio.
 

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Discussion Starter · #17 · (Edited)
I do not see a brown/red in that section of the ETM. Please confirm it is terminated by a pin (male), not a pin bushing (female) - makes a big difference.

The ETM states "AS OF MY 1986" in the upper right corner which leads the reader to believe there were no changes in that harness up to the end of production. I have seen discrepancies and variation in wiring diagrams and ETMs however. If you can provide a list of what wires you were able to accurately place in which locations, maybe we can solve it by process of elimination. A picture would help as well.
That's a great idea - from the black fabric wiring loom, there are 11 wires with "female" connectors that each have a respective space in the 14-pin connector. I'll take a picture later this afternoon and post. If you look at the pictures in my first post, the wires dangling with the bushings on them (there are 11) that each fit into the black connector which has 14 holes. Once each wire is in position, the plastic cover on the 14-pin connector closes, then mates with the 14-pin male connectors on the ECM,
 

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Standing by for the picture - sounds like the brown/red has a pin bushing (female), just like the rest of the leads from your broken connector. If this is true, I think we can safely assume all those leads belong in that connector and we can narrow it down to one wire that might be mislabeled in the ETM.
 
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