[Lumps!] wiring

Lumps
1

My interior is so pretty, I don’t relish climbing in there with a
bunch of tools taking the console apart to trace down a fuel pump
wire in my 90 XJS. I read in another set of instructions from JCI
that any black/slate wire left over from the jag harness can be
tapped into to drive the fuel pump. I have Howell’s aftermarket
harness which has a dedicated relay to the fuel pump. Which wire
is it best to attach to, and where is it? Any guidance? Since I
don’t know squat about wiring please advise precisely which wire
goes where.

On my suncoast 7 wire engine function harness, there’s a ‘‘coil
negative’’ for the tach. Obviously this is the tach signal wire, and
it looks like it’s supposed to attach to the negative terminal of
the coil. I have an LT1, with the coil mounted on the front of the
block. Tapping into the negative terminal wire at the coil seems
to be the right thing to do, but I’m unsure. Am I on track here?

And you’d think the electric fans would be simple enough, but I
read the ECM grounds the fans to start them. Does that mean then
that the fans are fed on one side from 12V switched positive, and
grounded through the relay?–
Dan Root 90 xjS drop top/LT1/4L60E
Livermore, CA, United States
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2

In reply to a message from Daniel Root sent Thu 31 May 2007:

Dan:

I am certainly far from being an electrical genius.
I am not familiar with the XJS set up. but, here we go:

  1. I removed the right cheek panel and found the big harness going
    back to the rear of the car where the pump is located. I identified
    the fuel pump wire by color. I think I also confirmed by applying
    powere. That is where I spliced in the 12v switched power from the
    dedicated relay. I could have done it in the engine bay.

  2. The tach wire is easy. Remeber, we worked on the diagram in the
    JC manual until we figured out it was updide down when compared to
    the car. Yes, tap into the negative.

  3. The PCM uses green to provide one ground to one relay for one
    fan. It uses blue to provide a ground for another relay for the
    other fan. You need switched power to the power leg of the relays.

  4. You will also need a means to run one fan when the compresor is
    engaged. I used a third relay. But, it must be triggered by the
    switched power to the compressor. That is to complete the ground
    and energize one of the fan relays by tapping in to the green or
    blue as in 3.

Andrew, If I am way off track, catch us!!

Carl–
The original message included these comments:

My interior is so pretty, I don’t relish climbing in there with a
bunch of tools taking the console apart to trace down a fuel pump
wire in my 90 XJS. I read in another set of instructions from JCI
that any black/slate wire left over from the jag harness can be
tapped into to drive the fuel pump. I have Howell’s aftermarket
harness which has a dedicated relay to the fuel pump. Which wire
is it best to attach to, and where is it? Any guidance? Since I
don’t know squat about wiring please advise precisely which wire
goes where.

–
Carl Hutchins
Walnut Creek, California, United States
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3

Just some notes here- there are some easier ways to do
these things:

  1. Fuel pump setup is somewhat similar on the XJS, but
    remember the relay is in the trunk, not engine
    compartment, so some minor rewiring is required there
    as well

  2. On the Tach, just use the tach output from the PCM-
    much simpler. If the PCM harness does not have a tach
    output, ask the wiring harness mfr for one. It take 2
    seconds to add it.

  3. For the fans, the PCM has the power to control the
    fans itself, including during AC operation. The stock
    GM arrangement uses a pressure switch (in the high
    line, which Dan has) to turn on the fans when AC
    pressure gets to a suitable point, and not below. That
    is most economical as far as noise, wear and tear,
    etc.,. Although having the fan relay tied into the
    compressor power will work, it will also potentially
    overcool the engine, and could possibly interrupt
    cooling at freeway speeds (where both the radiator and
    AC condenser) are getting enough air anyway…

The factory wiring diagrams show these circuits- so
far those arrangements have worked fine for me

Andrew____________________________________________________________________________________
Yahoo! oneSearch: Finally, mobile search
that gives answers, not web links.
http://mobile.yahoo.com/mobileweb/onesearch?refer=1ONXIC

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4

In reply to a message from A sent Thu 31 May 2007:

Thanks to Andrew and Carl,

Yeah Carl, I remember that upside-down picture issue, now
that you mention it. I was all set to tap that coil lead,
cuz that’s what I had to do on my last project. Logic says
there has to be a better way, which is why I posted the
question. As you can see in the response, another solution
is cleaner and neater.

I spent a lot of time hitting the manuals last night. Andrew
confirms much what I have read, and provides clarity to the
confusing parts. It’s really helpful to have the teacher
explain what the textbook says. Thanks.

BTW, Suncoast didn’t manufacture my engine function harness.
I bought a bunch of Suncoast’s stuff from a local
distributor, and I assumed the engine function harness was
theirs as well. Turns out the little harness is from Jaguar
Specialties. It keeps the splicing and tracing to a minimum.

As far as the fans are concerned, I have bench tested each
motor to determine which is lead is positive and which is
ground. As Carl points out, the positive lead will be
connected to the lead from the relay, and the other will be
grounded.–
The original message included these comments:

  1. For the fans, the PCM has the power to control the
    fans itself, including during AC operation. The stock

–
Dan Root 90 xjS drop top/LT1/4L60E
Livermore, CA, United States
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5

In reply to a message from Daniel Root sent Thu 31 May 2007:

I’ve used a couple of Howell’s harness’s and purchased a vss
sending unit for my xjs from them. Very good quality stuff. Did you
get the universal harness? I’ve used two of their caprice harness’s
and there is a tach wire provided in the harness.–
Rob Wade
Windsor Ontario, Canada
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6

In reply to a message from Rob Wade sent Thu 31 May 2007:

This is my second lump using a howell harness. They make good
stuff, but you will find mistakes. Their customer service is good,
too, so even if you find a mistake, they’ll help you sort it out.

I started this project at least a 18 months ago and it’s been
collecting dust for more than a year. It was mostly done, but
circumstances being what they were, I just couldn’t work on it.
While it was sitting, life went on, so we lost a several documents,
including Howell’s manual with the LT1 specifics. You’re quite
right, there’s a tach wire in the howell harness, but without
instructions, I couldn’t tell if it was an input or an output.

I did manage to keep JCI’s instructions from the last project, but
those instructions confused me even further than I normally am.
Apparently the coil output isn’t used in their setup, and JCI says
to tape it off. This time around I went with Suncoast.

Come to find out today from Andrew, the tach lead in my howell
harness is an output that mates up to the engine function harness
from Jaguar Specialties.

I didn’t get the VSS sender from Howell. The VSS and speedo is an
issue I expect to deal with tomorrow, but it sounds like I might
need more parts.–
The original message included these comments:

I’ve used a couple of Howell’s harness’s and purchased a vss
sending unit for my xjs from them. Very good quality stuff. Did you
get the universal harness? I’ve used two of their caprice harness’s
and there is a tach wire provided in the harness.

–
Dan Root 90 xjS drop top/LT1/4L60E
Livermore, CA, United States
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
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7

In reply to a message from Daniel Root sent Fri 1 Jun 2007:

Good luck with it…hope you get it figured out.–
Rob Wade
Windsor Ontario, Canada
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8

Is there a diagram out there anywhere for adapting chev ccc engines
to our xjs?
Bought a 82 with a 84 chev 305/700r4. need to wire it. The PO did
it with the computer but didnt wire up much more then ecm and fuel
guage…–
Blackkat
Brier, WA, United States
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–

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9

Get yourself the XJS shop manual (factory book, not Haynes) and go for it. That’s all you need…

Andrew
www.JaguarSpecialties

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10

In reply to a message from Blackkat sent Fri 6 May 2011:

A is right. Factory manual only, please. Except for what was jaguar
and remains Jaguar. And in that case, there are much better sources
for schematics than Haynes. It did nothng but confuse me.

If your car runs, he had to do mre than the PCM (ECU) and fuel
guage. No reason to mess with the fuel guage in the conversion
process. It remains all Jaguar.

Study what you have tht works and what you need to make work and
report back. I and they, mostly them, can straighten it out just
fine.

Think temperature guage, oil pressure guage, alternator, starter
and fuel pump for starters.

Carl–
The original message included these comments:

Bought a 82 with a 84 chev 305/700r4. need to wire it. The PO did
it with the computer but didnt wire up much more then ecm and fuel
guage…

–
Carl Hutchins 1983 Jaguar XJ6 with LT1 and 1994 Jeep Grand
Walnut Creek, California, United States
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11

In reply to a message from Blackkat sent Fri 6 May 2011:

Best wiring diagrams are here:

http://www.captainjaguarscathouse.com/Electrical_Reference.htm--
lockheed 92 XJS Cpe/97 LT1 Miami FL/ 96 XJS Cv 4.0 Austin TX
Austin, TX, United States
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12

In reply to a message from lockheed sent Sat 7 May 2011:

Yup, a great place for the Jaguar part of the cat. But
the ‘‘Correct’’ GM factory manual is essential to get the engine hook
up.

Off hand, I don’t know where he is going to get a signal for the
Jaguar speedometer.

Carl–
The original message included these comments:

Best wiring diagrams are here:
Captainjaguarscathouse.com

–
Carl Hutchins 1983 Jaguar XJ6 with LT1 and 1994 Jeep Grand
Walnut Creek, California, United States
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13

In reply to a message from cadjag sent Sat 7 May 2011:

Thinking very seriosly of just pulling all the computer crap and
going without… carb/intake/dist–
Blackkat
Brier, WA, United States
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14

In reply to a message from Blackkat sent Sat 7 May 2011:

The FI and electronic ignition is light years ahead of carbs and
points.

Not that hard to assimilate, if one goes at it systematicly

As I asked before, what doesn’t work on your car? Most here can
steer you right with specific insrtructions.

Take it from a guy that jumped from old tech to installing the LT1.
Sounds confusing, but again, circuit by circuit gets it done.

You will not regret it.

Carl–
The original message included these comments:

Thinking very seriosly of just pulling all the computer crap and
going without… carb/intake/dist

–
Carl Hutchins 1983 Jaguar XJ6 with LT1 and 1994 Jeep Grand
Walnut Creek, California, United States
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
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15

In reply to a message from cadjag sent Sat 7 May 2011:

Ok… stepped back and took a breath… all good now…

Jag speedo is getting its signal from the fact that its a cable
driven… as is the 700r4 afaik…

what I di need to find is a signal for the VSS as it seems the
original one (84 camaro) got it from the speedo in the camaro…–
The original message included these comments:

Off hand, I don’t know where he is going to get a signal for the
Jaguar speedometer.

–
Blackkat
Brier, WA, United States
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16

anyone in the area of chandler, mesa ,queen creek has some free
time? if so I would like to stop by and check out some wiring
questions. 480-924-1746. thanks mike.–
sfga11
san tan valley, az., United States
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17

What are you trying to wire???

Andrew
Jaguar Specialties--------------------------------------------

anyone in the area of chandler, mesa
,queen creek has some free
time? if so I would like to stop by and check out some
wiring
questions. 480-924-1746. thanks mike.

sfga11
san tan valley, az., United States

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