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1973 450 SL
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Discussion Starter #1
Last Summer some of our D-Jet owners discussed this topic here:

1973 450SL Engine Harness Parts Needed

The consensus of that thread leans toward purchase of a new engine harness. I appreciate that for our members who are interested in OEM integrity.

My harness was in need of some work - dried out, brittle, cracked, connectors. Google led me here:

TheSamba.com :: View topic - Type 3 D-Jet Harness Thread

Some VW D-Jet guys have built harnesses using double cantilever terminals. AMP/Tyco has made these for Bosch / Lucas since they discontinued the male spade to female rolled clip terminal in our harnesses. If you buy Bosch part 1287013003, you are buying an L-Jet connector with these terminals.

VW 411/412 enthusiast Ray Greenwood has found a way to adapt these 2 pole connectors to fit our injectors and sensors. Simply cut back the housing to its base. His expertise got me interested in building engine harnesses. Ray is of the opinion that OEM D-Jet harnesses are flawed in design at the terminals. Ray says that electrical resistance is critical at every connector except the TPS and Start Valve. I tend to agree with him because I have seen the noisy signals running through my harness on an oscilloscope. I am not all-in yet, but I have been experimenting with this since last Fall.

I harvested connectors from mid '90's Audis, Volvos, V-6 Saabs and V-6 Saturns. The Audi ones are the most versatile because they can be separated from thier housings (pink plugs in the pictures). These connectors are rectangular and fit snug in our injectors and start valve. They require a little dremel work to fit our air temp and coolant temp sensors.
 

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1973 450 SL
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Discussion Starter #2
More 2 Pole Applications

If you skip the L-Jet housing, you can use OEM boots. My harness had really bad connectors at the front of the engine. The last pictures are L-Jet connectors without housings at T1, T2 and Start Valve on my car. Running fine so far.
 

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1993 600SL, 1973 450 SL,1982 380SL,1998 SLK 230, 1968 Firebird, 2001 Dodge Ram 4x4,2005 Ford Escape
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Woohoo ! You are my hero ! My harness is old and brittle. As part of the full resto I am going to either buy or build that harness. Keep up the good work on this thread. Let's get the part numbers and sources (hopefully at less that we can buy the harness !) so we can re-create this harness ! Good work and very timely ! Thanks. PS, been busy, but I'll take those clamps. Don't think I need that AAV (yet) though ! :D
 

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1973 450 SL
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Discussion Starter #4
MPS and TPS Applications

The 4 pole connector from an Audi fits our MPS. If you don't like the housing and boot arrangement in the picture, you can use the OEM boot. I have that but could not find a picture - will take another one soon.

I had a hard time finding 5 pole connectors for TPS and early pulse generators (the kind with the female socket at the pulse generator). The one shown is from a V-6 Saturn. I recently found some Audi 5 pole connectors. I need to test fit and take pictures of those.
 

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1973 450 SL
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Discussion Starter #5
Part #s and Sources

AMP 927771-3 terminals from onlinecomponents.com - I bought 100 on a roll and separated them myself and saved a few $$. Our harnesses require 30 - 35 terminals depending on the TPS (4 or 5 wire) and Pulse Generator (5 pole socket or fixed lead to 5 pin connector). My car requires 31 terminals.

AMP 928516 is the 2 pole housing
AMP 928517 is the 2 pole plug
Audi / VW 443 906 232 is the whole thing I think

AMP 962443 is the 4 pole housing
AMP 962444 is the 4 pole plug
Audi / VW 4A0 906 234 . . . (the 4A0 is not a typo - I checked 3 of them)

AMP 929554 is the 5 pole housing
AMP 929555 is the 5 pole plug
Audi / VW 443 906 235 . . .

I have not cut the 5 pole housing because I only have two of them on hand. I got all these from U-Pull-&-Pay in ABQ; I have not verified the Audi / VW info, just reading numbers on the housings. One thing I forgot to mention about these Audi plugs - terminals can be inserted and removed easily with a pin or paper clip. This is nice for assembly and future repair.

The Bosch / Lucas boots can be puchased from B&B Auto Parts
75-76 Cosworth Vega EFI Harness Rubber Boot Set

I bought a roll of ignition wire insulation from a local speed shop - more than adequate to protect what I have made so far. I am using the correct color wire harvested from salvaged engine harnesses from 107s, 108s, 109s and 116s. The wire from the ECU plug to the branch split has been well preserved in all my salvage harnesses. Some of the VW guys are using MIL Spec wire and gold plated terminals. As I said earlier, I am in the experimental phase.

I am using a Paladin 1302 crimper with a 2033 die. It took about 3 crimps to get the hang of it. Got these items from Amazon.
 

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1973 450 SL
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Discussion Starter #6
Committed and Connected

I collected all the pieces I needed to mend my engine harness. I decided to use the OEM plug boots. I also decided to use connectors upstream of the injectors to simplify installation and removal and provide an electronic test point.
 

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1973 450 SL
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Discussion Starter #7
More Pictures

The first picture is an example of what my assembly looks like for an injector. I made nine of these with fresh, correct colored wire for the injectors and the start valve.

I sat on these for a few months before I decided to cut my operating engine harness (fixing what was brittle and cracked, but not broken).

I cut the injector wires at the waist of the plug boot; where the boot gripped the leads. In each case, this revealed fresh, pliable wire. I removed the brittle black insulation and soldered 1mm pin bushings seen in previous pictures (female on harness, male on injector pigtail). Heat wrap came next. It is arbitrary for injectors but I adopted the Bosch convention of signal wire a pole 1, ground at pole 2. I used a woven wire jacket that is supposed to resist 1100F and stop protect from fuel and oil too.

The last pictures show the lines installed. I still need to tidy up the insulation at the connectors and boots. Electrical tape is not good - I'm thinking heat wrap again.
 

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1973 450 SL
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Discussion Starter #8
MPS and TPS too

When I did the pressure sensor, TPS, air temp and coolant temp sensors, I had enough slack in the wire to cutback to fresh wire. The pressure sensor lead was in the best shape - true on 5 salvage engine harnesses I've pulled.

My pressure sensor plug was installed inverted - no telling how long the car had been running that way. The 4 wires introduce inductance change across 2 pickups inside the MPS so I guess it doesn't matter. I decided to reassemble it the way Bosch built it - it runs that way too.

Ever since I was a kid working on go-karts, lawnmowers and motorcycles, I have been able to convince myself that things run better, run faster, jump higher after a project like this. It is more fun if you are able to do that.
 

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'71 250, '78 450SLC 5.0, '78 450SL, '81 380SLC 5.6, '89 260E, '15 Kia Sorento
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Fascinating thread. I am in awe of the things you guys can do on this forum.
 

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'72 350SL, '85 300D, '98 E320, '19 Subaru Outback (sold '14 GLK250)
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Looks like a good job Cush. One of these days I would like to do something similar.
 

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Outstanding Contributor
450slc5.0cab 280sl5sp 280se4.5 500seAMG +250seStkW108 350sl4spdX3 500secEuro
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Fascinating thread. I am in awe of the things you guys can do on this forum.
Dan:
There is a good example of how d-jet parts can be valuable. Even good wire boots can be valuable. I think I recently sold a throttle position sensor with the plug and wire boot (but can't recall the condition) for about $15 on ebay. I had no idea anyone here could have been interested in it if it had a good boot. I think the idea is to find more readily available non-oem parts though.

So perhaps snapping some pics of all the good wire boots in your engine bay would be helpful here.
 

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1975 Mercedes 450 SEL
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Wow very impressive work your giving me Ideas . Do You have a 1975 450 Harness in good condition ? . Don't know yet if I need one but should learn that soon I expect .
 

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1986 560SL: '84 500SL: '84 280SL 5 speed: other 107s
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Wow very impressive work your giving me Ideas . Do You have a 1975 450 Harness in good condition ? . Don't know yet if I need one but should learn that soon I expect .
When you decide post the request in the for sale wanted sub forum. Either that or send a PM.
 

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1973 450 SL
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Discussion Starter #14
Spare Engine Harness Rebuild

I pulled the engine harness from 107 044 12 008700 a few weeks ago. I got out my bits and pieces referenced earlier in this thread and am rebuilding it. Someone cut the lead to the MPS then left the MPS??? (which I have now) - no other damage to the harness other than brittle injector boots, hardened conduit and a few cracks in the wires closest to the engine. I have enough harnesses from 116s to cut and replace fresh wire in the correct colors. I also like the modular approach using 2 pole connectors at points in the harness that are not as vulnerable to heat. This way you can replace pigtails as they wear and become brittle.

This is an early D-Jet engine harness with the plug at the pulse generator. I am going to replace the PG plug to accommodate double cantilever terminals. I built a pigtail about a year ago to adapt old PG plugs to connect to later harnesses - just haven't decided what to do with this particular harness yet. I will also cut and replace the plug at the TPS. I want to find a 4 and 5 pole version of the connectors in pic 2 before I do this.

I have 11 OEM 2 pole connectors (injectors, T1, T2, start valve) that hold the rolled clip terminals. I may build up a set of pigtails from those to retain the option of returning to original. I am a big believer in the double cantilever terminals in pic 6 however.

The best part about this method of harness restoration is that you can disassemble it. So far, connectivity is very good with resistance readings at less than 1 ohm through the harness (.2 to .3 ohms).
 

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Discussion Starter #17
I found a better wire jacket recently. I had to change 8 x O2 sensors on 2 BMWs (all from Bosch) and noticed the wire jackets and wires inside them were in remarkably good shape after 100000 miles in a very hot environment. I harvested these wire jackets and tested them on the pigtails I have been making - I thought about using the wire too but did not like the core as it was not 100% copper.

The wire jacket has an inner lining of woven fiber surrounded by an outer sheath to protect against corrosive fluids.

This wire jacket mates well with various connector boots - an area I have struggled with using the speed shop stuff posted earlier. I'm using this jacket to rebuild a '75 D-Jet harness. I grabbed several sections from salvage cars at UP&P last week and will re-jacket the leads on my engine harness. I got some of it done today.
 

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Discussion Starter #18
My engine harness and the '75 SLC harness are done - used the new and improved wire jacket. I also reformed the sagging firewall liner with a heat gun then re-glued it.
 

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Discussion Starter #20
Thanks Dragon - I've been running this harness for over a year now. Intermittent poor running problems have disappeared. I am sold on the newer terminals to improve signal to the ECU. I've said it before, but I really wonder how much money was thrown at sensor replacement when the problem was in the design of the harness.
 
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