Rebuilding Facelift Engine/Fuel Injection Harness

OK, so I’m ready to start my long process of building a new harness for my 1996 Jaguar XJS. I pulled a harness off of a 1995 car with a LHE3340BE. The latest part number for my car was LHE3340BG, I don’t know what the difference is, but I will try to find out before I start by double checking all connections to make sure they match.

So far, the only thing I noticed on the harness I took off was that there was a ground point at Coil #1 that my car doesn’t have. It doesn’t show up on the electrical diagram, however this will serve as a good segue for my question:

What do the circles and dotted lines mean in the wiring diagram? I’ve attached it for reference. For example, if you look at the Crankshaft Position Sensor, you’ll note two circles with dotted lines heading for another set of circles at LI189-23 and LI189-26. What does this mean?

Thanks.

The crankshaft sensor will be connected using a screened cable to protect the signal from electrical interference - that is what the hoop and dashes mean. Typically, these will be earthed at one end only.

kind regards
Marek

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I could not find anything obviously unique with that wire, however I have not removed all of the electrical tape and loom. I’m hoping something will appear much more obviously unique once I do that.

Is there a preferred wire I should use when rebuilding these lines? I intend to stick with an 18 gauge wire. I think I will be using SXL wire, but I’d love to know if I should reconsider that.

I did find something unusual that I cannot seem to find on the wire diagram. It’s some kind of fuse? I have pictures of it below. What is it, and how would find a suitable replacement. I’m looking to replace all connectors, and I may as well include this as well. Thanks.

Looks like inline fuse or perhaps a diod…?
Whatever wires you use, make sure it has temperature rating higher than 250 F. This is the only way to ensure longevity. Gauge 16 or 18 for the injectors and the other components/sensors should be fine. The coax/shielded wire for the crank sensor is probably difficult to source – the ones sold for use in electronic equipment are not suitable for the engine bay. The coax that will work is sold online, but often you need to get a whole spool…let us know if you find a retailer that will sell by the foot.
Good luck,
Steve

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I did find something unusual that I cannot seem to find on the wire
diagram. It’s some kind of fuse? I have pictures of it below.

Looks like a diode. Diodes are usually installed for one of two reasons:

  1. To prevent powering up one thing from backfeeding to power up
    something else that you don’t want powered up. For example, in the circuit
    that engages the A/C compressor and turns on the electric radiator fan, there
    needs to be a diode somewhere so the fan being operated by the thermal
    switch in the water pump inlet doesn’t bring on the A/C compressor.

  2. For inductive loads, switching the load off can cause a reverse voltage
    spike of several times the system voltage, and this reverse spike can
    damage transistors and etch away at contacts. A diode may be installed to
    deal with these voltage spikes before they can do any damage. Many
    modern relays – which have a coil inside and therefore are an inductive load
    – come with either a diode or a resistor built in to protect whatever
    transistorized controller is operating it. The resistor is more common there
    because it isn’t damaged when somebody wires the thing up backwards, but
    if the device is to be built into the harness instead there isn’t a concern about
    being wired backwards.

– Kirbert

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http://www.aircraftspruce.com/catalog/elpages/shieldwire.php

I found this for shielded wiring?

I wonder why the diode isn’t shown on the wiring diagram. How would anyone know to look for that blown fuse? I suppose I should just reuse that piece.

I intend to stick with an 18 gauge wire. I think I will be using SXL wire, but I’d love to know if I should reconsider that.

That’s what I used. It’s held up well.

. I’m looking to replace all connectors, and I may as well include this as well. Thanks.

If had it to do over again I’d use Weather Pack connectors and special crimper. www.delcity.com

Ed Sowell

'76 XJ-S coupe, red

http://www.efsowell.us

.

Ed, thanks for the advice, I’ve definitely read through your posts several times. I will stay with the same connectors since I don’t intend on repining both ends of every connection point. I think the facelift connectors work well enough, I can see how the older style connectors you fought with mught not hold up as well.

18awg SXL it is then. Now it seems I’ll be sprinkling in the shielded wire I found at aircraftspuce.com at the Crankshaft Position Sensor, both knock sensors and all four oxygen sensors.

“. I think the facelift connectors work well enough”

I agree.

Ed Sowell

'76 XJ-S coupe, red

http://www.efsowell.us

After spending time identifying and hunting down retailers that sell connectors, I’ve found that all of the connectors seem to be made by good companies and should work well. I’m even wondering whether I should just concentrate on replacing the pins and leaving the connector housings alone and reusing them!

Sumitomo, Delphi and Tyco/Amp seems to makeup 90% of the connectors on the harness.

I’ve had to outsource one pigtail for the alternator which was somewhat difficult to find.

Is it worth replacing all connectors, or should I just focus on new pins?

Here’s another, more economical retailer of shielded cable…

Would using twisted wires for all harness wiring make a difference? There are suppliers that will sell twisted pairs of 18awg GXL wire. Perhaps I should consider using that, or is it not worth the trouble?