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D-Jet Engine Harness

42K views 182 replies 20 participants last post by  MBGraham 
#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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#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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#3 ·
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
 
#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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#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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#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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#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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#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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#11 ·
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.
 
#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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#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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#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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#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.
 
#21 ·
New Option for 5 pole D-Jet Connector

I went for a parts survey at UP&P last week. Scored a nice Zebrano wood shifter from a 116, several of the connectors that I like. Only one 5 pole connector like I've been using (the pink ones from Audi / VW). I also found a new 5 pole connector to experiment with:

MB Part # A 034 545 41 28

The thing that caught my eye with this one was its extra width having 2 plastic spring clips. I thought these might fit well in the TPS and old style pulse generator. Not so fast - Dremel work was required. This part is $1.80 at OE Discount Parts.

After some work, it makes as good or better fit in the TPS and PG than the Audi connector. A benefit I did not see at first was how the D-Jet boot works better with this connector due to the shape of the aft end (flaring out to match the shape of the boot). When fully inserted, the boot actually helps hold this connector in place.
 

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#23 ·
I bought some 90 degree boots here:

Bosch D-Jetronik

These work well for the air temp sensor, coolant temp sensor and start valve. I installed them last night. I had been using the boots that cover the terminals at the fuel pump. These are better because they are longer and seal around the lip of the sensors / start valve.
 

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#24 ·
Brad - is it possible to retrofit by feeding the connectors for the temperature and other 2-pin connectors through those boots without cutting the wires? Are those boots from Germany the best choice for a retrofit?

From memory, I think both my temperature sensor boots need boots as well as one other. Probably one or two injector boots too. Self amalgamating tape works but isn't too pretty!
 
#25 ·
is it possible to retrofit by feeding the connectors for the temperature and other 2-pin connectors through those boots without cutting the wires?
Graham,

The connectors will not feed into the small opening for the lead in these boots. If you have the original connectors, the terminals were heat crimped into place. If you want to keep the original wires, it is possible to dremmel cut the connectors at the heat crimps, remove the terminals, install the boots, then insert the terminals into new connectors which Repro parts also sells.

I got the link for this supplier from the Oldtimer's website, chapter 10 - engine harnesses. Yes, the company is in Germany. Parts are not cheap, but I liked the service and quality so the value is there; so far, this is the only place I have found for the 90 degree boots.

As you know, I do not use the rolled clip terminals when I work on engine harnesses. As a result, I also do not use the original connectors - the ones I use are easy to disassemble. I'm rebuilding an engine harness this week; happy to shoot you some pictures via PM if you like.
 
#26 ·
Graham,

The connectors will not feed into the small opening for the lead in these boots.
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I'm rebuilding an engine harness this week; happy to shoot you some pictures via PM if you like.
All connectors on my car are original 72's type. Maybe the bottom of the smaller diameter end of those elbow boots could be slit and then re-glued or taped closed?

Interested to see your harness build. Either posted on BW (isn't there an existing thread?) or by PM.

My harness is still quite good. Just the temperature boots and one or two injectors a bit ragged. I should have a closer look and see just what would be an improvement.

Cheers
 
#27 ·
I should have a closer look and see just what would be an improvement
I'm sold on the terminals described in post #1 of this thread. Oscilloscope readings with the rolled clip terminals were noisy - very clean with the double cantilever terminals. This resonates with what Ray Greenwood posts on the VW thread referenced in post #1 .

The harness I'm working on this week is from an early '73 (plug at the pulse generator).
 
#29 ·
I decided to re-read this whole thread and also Dr.Djets page on harness rebuilding!

I now understand what those AMP 927771-3 terminals are. Basically still need to be properly crimped, but can be easily removed from plastic plug block if desired. Crimping spec here. I used something similar for my boat's multi-conductor radar connector. I bought a good Radio-Shack crimper, but in end I think I also soldered the conductors to the terminals.
 
#28 ·
Hi Brad,

you have done an interesting job here! I will look at those AMP Junior contacts and how they can be attached to the original ECU connector. If successful, I will add this to my engine wiring harness article. For the other connectors, we have the luxury of a replication of original connectors and contacts and rubber sleeves in Germany as mentioned in my article. With those, the harness will look totally original with the exception of the missing Mercedes star on it. :wink

BTW, repro-parts.de has done the rubber sleeve for air temperature sensor and cold start valve after I initiated it. Happy to see that you like it.
 
#30 ·
Hi Graham,

what I understand is that the AMP contacts do not fit the original connector without cutting out a bit of it. But then you can crimp them on the new wires and insert them in the connector.
 
#31 · (Edited)
Re-reading one of Brads earlier posts, he said:

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.
So sounds that most will fit, but not all.

I just checked out my car:
Injectors - 5 boots OK, 3 still in place but distorted.
TPS - completely broken
MPS - good
Triggers - good as far as I could see without removing
Temperature sensors - both gone (taped up)
100C switch - taped up.
Cold start valve taped up.

So far as I can see, wiring looks OK. Car runs fine, so no problems - yet.

Not sure that the boots really do much to protect the connectors. Loose fit and no real seal. But they do make things look neater! Might be an idea toalso seal wire entry points with grease or an electrical sealant?

Rather than complete rebuild, thinking that I could try two approaches:
- buy new boots and try a slit and glue/tape fix.
- cut back wires and install new connectors with short wires plus boots. Then solder to existing harness. Probably have to remove harness? Or feasible to do in place?

If have to remove, may be better to find a harness from a scrapped car and work on that first?
 
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