Junior Timer Connectors

[Tom]

Thought I’d do a post on “Junior Timer” connectors, since they showed up on so many Porsches over the years. On some cars, like the 944, nearly all of the engine harness connectors are Junior Timer connectors, including the injectors, DME temp sensor, knock sensor, speed and reference sensors, AFM, TPS, ISV, etc. I know even the 991 still used this style connector, since I use it on my Track Nanny....

Unfortunately, it’s common to have the wires fray in these connectors and cause all sorts of problems. The speed and reference sensors and the fuel injector connectors both cause no-start problems when this happens. Other sensors are similarly prone to this problem, but often go undetected longer if the car still runs.

It seems that the wires are prone to fray due to the hard potting material (resin) Porsche used under the rubber boots (on some models/connectors), presumably to seal the connectors and add strain relief. The wires are encased in this hard resin, so when the wires move and vibrate over the years, they get abraded right where they exit the hard plastic, and all bending force is concentrated right at that one spot. Over time, that wears away at the wire insulation and, eventually, at the copper strands inside.

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I cut off all the injector connectors on my 951 since one was bad. This one was one of the ‘good’ ones after stripping back the rubber boot. The wires weren’t touching, so it ‘worked’ but moving the wires even a little bit would have shorted them out.

If you are trying to repair a bad connector, be aware that there are two families of connectors that seem the same, but really are not. Most older Porsches use “Junior Timer” (JT) connectors, whereas most of the modern replacement connectors are “Junior Power Timer” (JPT) connectors. They are plug and play compatible, but if you want to repair a connector by replacing the terminal contacts, it’s important to know which you have. Junior Timer terminals have only one latching tang, whereas Junior Power Timer connectors have two. You can get away with using the wrong type, but it could cause extraction or retention problems down the road. If you look at the mating face of a connector, it’s easy to see the difference. A + shaped opening with two slots for pin extraction means it's a JPT connector that takes terminals with two latching tangs. A T-shaped opening with one slot means it’s the older JT style.

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The slots in the connector that create the T or + shape let you push an extractor tool down the sides of the pin to compress the latching tang(s) and remove the pin. Unfortunately, on factory original connectors, Porsche makes it very difficult to re-use the connector housings because they back-potted the connectors with resin. As such, most people just buy all new connectors. That said, on some connectors -- like the main DME and KLR connectors on the 951, there is no back-potting, and the pins can be removed with extractor tools like the ones shown below.

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These are Durite 0-703-99 pin extractors. In recent years, a number of automotive pin extractor sets have become available, one cheaper than the next, so it's worth a quick google search before buying this particular set.

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This tool has two blades, one for each tang on the JPT terminal pin.

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And this tool is for the older JT connectors, like the ones on the main 944 DME connector. Once the tool is slid all the way down the channel, it depresses the latching tang so that the wire can be pulled out the rear with the terminal pin still attached and unharmed.


While they do make hand crimpers for these terminal pins, I've yet to find one priced for the home mechanic. By luck, however, I discovered that my WeatherPack crimpers work very well. They are Delphi 12014254 crimpers and are still about $100, but they make great crimps on these pins.

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Not 'perfect' for the true crimp connoisseur, but it's a very secure 'forever crimp.'


A nice JT replacement for the 2-pin 944 fuel injector connectors is TE Connectivity #827551-3. It has an integrated spring clip that won't go flying across the garage like the originals.

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The terminal pins come in many variations, for different sized wires, etc.

A useful 1-tang terminal pin for the JT connector is: 925590-2

A useful 2-tang terminal pin for the JPT connector is: 965901-1

Online electronics retailers like Digikey and Mouser have all these parts on the shelf and ready to go.

[Zirconocene]

One of the things that I have found in digging into these issues on my S2 and 928 S4 is that I'm not sure that every connector in the harness is able to be depinned. If you look closely at some of the OEM connectors that are original to the car you can find 2 rectangular indentations, on the circular part of the housing. I believe that Porsche put these indentations in and they make it impossible to remove the wires, even if you can depress the tangs on the connector. I haven't cross sectioned these connectors to verify but I think that this is a further safety feature on the harness.

Cheers

[Tom]

One of the things that I have found in digging into these issues on my S2 and 928 S4 is that I'm not sure that every connector in the harness is able to be depinned. If you look closely at some of the OEM connectors that are original to the car you can find 2 rectangular indentations, on the circular part of the housing. I believe that Porsche put these indentations in and they make it impossible to remove the wires, even if you can depress the tangs on the connector. I haven't cross sectioned these connectors to verify but I think that this is a further safety feature on the harness.

Cheers

Well, there's zero question in my mind that Porsche made it impossible to de-pin some of these connectors (in any practical sense anyway). I took the injector connector in my pictures above and dug in further. The rubber boot was glued on tight (you can see glue everywhere in the pictures), and the potting material goes in so deep that there's simply no way the pins can be pulled out. Even if they had no latching tangs at all, the pins are secured in place like a fence post in concrete. I do see the two stake marks you mentioned, and they look melted in place. I guess it's possible those are there as part of an automated assembly process, but whether intentional or not, it has the effect of further staking the pin (and its attached potting material) in place.

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I assume these are the stake marks you mentioned?

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Lightly ground, you can see the wires are entirely encased in the potting material.

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Here, it's ground about half way through the stake marks, and it's still full of potting material.

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After grinding down and picking out enough potting material, you can see that stake marks do seem to create an impression on the inside of the connector, and add another thing to keep the pin in place. I'm guessing the effect is even more pronounced when the potting material is still there. However you cut it, Porsche had no intention of people repairing these particular connectors with new pins.....

[Zirconocene]

That's a great set of pictures!

I don't think that I realized just how much of the potting compound was used originally; you're right, those things were never going to come apart cleanly.

Cheers

[ROB III]

Thank you for the ever expanding education!

[Tom]

Thank you for the ever expanding education!

Thanks, I figure the more we inspect and share stuff like this, the more we all end up learning. I'm no expert by a long shot though. But @Kroonwireharness is here and knows a thing or two about wiring...

[AudiSport]

I just ordered a bunch of parts to build my new MaxxECU harness. Wow there are a lot of variations on contacts and housings...

Here's a few extra parts that might help.

Wire seal
828904-1


Contact Tinned Copper contact instead of Tinned Bronze above
925597-1


Boot for 2 position connector
880810-1


If you need a 3 position for the ISC, I could only find it in a longer length connector (21mm vs 18mm)
282191-1


Contact for 3 pin
929939-1


Boot for 3 pin
880811-2

Use same seals as above.


Finding the 6 pin for the TPS is very elusive. But 944online carries a package with all the parts but the seals.
https://944online.com/engine-electrical ... ector.html

They also have other packages of connectors if you don't feel like going out on your own to assemble all the small parts.
https://944online.com/engine-electrical ... r-kit.html

[AudiSport]

Thank you for the ever expanding education!

Thanks, I figure the more we inspect and share stuff like this, the more we all end up learning. I'm no expert by a long shot though. But @Kroonwireharness is here and knows a thing or two about wiring...

They have a nice list of connectors on their site for purchase, shipping to the US makes it a bit prohibitive. I bought a used NA harness(cheap) to steal the firewall boot from to build a new harness. It just wasn't worth the cost to order from them.

[Dare]

Great info in this thread! Here are a few other tidbits from my notes...

Regarding mixing JPT and JT, I have found that the JPT receptacles are compatible with with the DME/KLR connector housings, despite the fact that Porsche used JT receptacles originally. Beyond the difference in retention tabs, the other notable difference between the two types is that the crimp area on the JT receptacles is rotated 90° relative to the contact surface, while on JPT receptacles it is straight-on.

You can see the difference here (JPT on the right, JT on the left):

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This rotation provides more room for the DME/KLR connector shell locking bar to seat in the housing.  However, in my testing, the locking bar still fits and holds the JPT receptacles in place adequately. This is convenient if you use JPT connectors in your harness builds, as it means you don't have to order different receptacles for the DME/KLR connectors.

As to whether you need to buy a special terminal removal tool, here's what I use:

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This is .032" safety wire folded back on itself. Works every time.

Finally, I have had good results crimping the JPT contacts using a Pressmaster 4300-3146 die set in their standard crimping tool frame (Pressmaster 4300-3149/AAA, a.k.a. Waytek 560). I got both at waytekwire.com.

[Tom]

I wonder what motivated all the little changes.... ?

As for terminal pins and connectors, there are indeed a lot to choose from. Although the big online electronics places are intimidating to use at first, they have nearly everything currently made and for the most part sell them cheaper than auto parts places that essentially charge you to find them... There's definitely value in buying an assembled batch of parts like the one 944online sells, but I'm guessing (without checking) that you can get all the same at someplace like Digikey or Mouser for considerably less.