I am trying to remove the TDC sensor from my ‘90 XJ-S for the purpose of replacing it.
I have disconnected the top and bottom connectors. I have tied a 3’ long piece of twine to the top connector and secured the twine additionally with electricians tape. My plan was to pull the harness out through the bottom, transfer the twine to the new harness and pull it back up, through all the various nooks and crannies, to the top.
A good plan on paper, perhaps, but not without its pitfalls.
The top terminal gets stuck somewhere just below the adjusting arm for the power steering pump. I can’t see exactly what the problem is. Does anyone know where the harness is binding up.? Do I have to move the power steering pump out of the way?
In my own defense, I have tried the archives, my JDHT Parts and Service Manual and various on line sources with no results.
Any guidance would be deeply appreciated.
Michael
Michael,
There is a clip midway on the sensor wire bolted to the block. If you can get a light to shine on it you should be able to loosen the screw enough to get the wire out and back in. I am attaching a couple of pictures for you to reference.
I haven’t tried it but you may be able to spread it open enough with a screwdriver to accomplish the replacement. The best access is from below.
Good luck,
Jeff
On my wife’s 1990 XJ-S convertible (5.3L w/ Marelli ignition) there were two clips holding the crankshaft position sensor cable in place at the left front of the engine. One was the one that Jeff shows in his picture. The other one is a little further up on the engine. I have circled both of the clip locations on the attached picture, although the lower clip and cable are removed in the pictures.
Hi Steve!
Thank you for your reply.
I AM referring to the CPS. In more than one on line discussion I saw
it referred to as TDC (top dead center) sensor and got that locked in
my brain.
How did you go about removing and replacing the harness. I look
forward to having “no problems”.
Thank you for your help!
Michael
Quoting Steve noreply@jag-lovers.com:
Hi Jeff!
Thank you for your response and the pictures.
I found the clip early on and was successful using a screw driver to
pry it open enough to free the harness. The harness now moves freely
for about 10" of travel, until it gets stuck down by the power
steering pump.
Thanks again for your help!
Michael
Quoting gcoder1 noreply@jag-lovers.com:
Hi Paul!
Thank you for your response and the picture!
I already found the bottom clip and have dealt with it (even a blind
squirrel will find an acorn once in a while). As freely as the cable
now moves within its 10" of travel, I never would have guessed there
was a second clip!
I see that accessibility might be a challenge. Any tricks you might
have up your sleeve for getting at the clip without dismantling the
whole front of the engine would be greatly appreciated.
Thanks again for your help!
Michael
Quoting “Paul M. Novak” noreply@jag-lovers.com:
I am always glad to help others on Jag-Lovers. I have learned so much here that I try to repay that kindness whenever I can.
Accessibility of the second upper CPS cable retaining clip bolt will likely be a challenge. It’s a ½” bolt and the only way I can see of getting to it, with everything installed in the engine bay, <img src="//jl-discourse-uploads.s3.amazonaws.com/original/2X/6/6c0d21907e62acb92c4f82c5ac9cfba58b7ea06d.jpg" width="690" height="388">is possibly by loosening up the power steering pump bolts and adjustment bolt, removing the belt, and lowering the power steering pump/reservoir outboard. You should not have to remove either of the hoses going into the rear of the power steering pump/reservoir. With the pump/reservoir out of the way you should be able to access the bolt holding that upper clip in place in order to remove and replace the CPS cable and run it through that clip. I have not done exactly that myself, but it does appear possible. However, that is a lot of work just to replace a cable. But, without moving the power steering pump/reservoir out of the way, I can’t see how you will be able to get a tool in there (with all the remained of the components in place at the front of the engine.
At this point I have the old radiator out to replace it, and I am doing a thorough cleanup and removal/replacement job of engine bay stuff. So I have excellent access to that area for pictures. The attached picture shows another view of that upper bolt and CPS cable retention clip in place and circled in red.
As an alternative, you might try leaving the clip and bolt in place and cutting the CPS cable if you can't get it free. Then you can try using something like a spot-tie to secure the CPS cable to the upper clip. That should keep it from getting damaged by rotating components at the front of the engine. Still, it's a very tight place to work in. I wonder how others have replaced that CPS cable.
Good luck and let me know if I can be of further assistance.
Regards,
Paul M. Novak
1990 Series III V12 Vanden Plas
1990 XJ-S Classic Collection convertible
1987 XJ6 Vanden Plas
1984 XJ6 Vanden Plas
1969 E-Type FHC
1957 MK VIII Saloon
Ramona, CA P.M.Novak7@gmail.com
Thank you for the advice and the pictures. Both helped a lot!
However, I discovered first, that even after backing the power
steering belt tensioner all the way down until there were no more
threads available, the belt, while loose, was still too tight to even
PRY off. I assumed the wrong belt had been installed by the PO, though
I couldn’t guess how he ever got it on there in the first place.
I eventually decided to cut the belt and remove it that way. After
laboriously backing off the other tension adjusting nut and moving the
power steering pump back out of the way, I discovered the retaining
clip in question had been removed already, and that moving the pump
back allowed me to pull the old CPS harness out and reinstall the
replacement. Happy days!
Next, I went to the local parts house and got a new belt that was
specified for my needs. When I compared it to the old belt, I fully
expected it to be noticeably longer than the one I cut off. It was not!
So what’s going on here? Do parts houses all have the wrong part
number for this belt?
The amount of adjustment available to relieve the tension on the old
belt was about 3/4 of an inch, with about 5" available to tighten the
tension.
I’m prepared to take my new belt back to the parts house and ask for a
slightly longer one, unless you or anyone else has a better idea, or
some insight specific to this issue.
Thanks again for all your help so far!
Michael
As I feared, the old belt and the new belt are each 42 1/2", which, as
you noted, is the correct length for my application. Now I’ve got to
figure out why I couldn’t get the old one off. I am obviously missing
something basic here. It’s not like I haven’t replaced more than a few
accessory belts in my lifetime.
Maybe I will find out the solution to my problem when I try to install
the new belt.
Thanks again for your help!
Guess what! The new belt went on without any struggle and the tensioner nut is now out about twice as far as it was on the old belt.
I guess I’m not very good at comparing old belts and new belts.
After hooking up the new CPS harness I still had no spark from the coil to the distributor cap. After replacing the Engine Speed Sensor harness I finally got spark to the distributor cap from both coils. Not exactly a bright blue spark, but at least a spark. But now I have spark from the distributor to the spark plugs on B bank, but not on A bank.
Progress, nevertheless!
How do you test the power modules/amplifiers?
I thank all of you for your patience with me and this project!
Michael
Thank you for your reply!
Actually, that’s the first thing I did. Not because I’m so smart, but
because someone I know who is, told me to. The A bank part of the
rotor was fried to a crisp. I replaced the cap and rotor with what
appeared to be “good, used” parts that I had on hand and actually had
the engine running, though only briefly, on what turned out to be the
B bank only. It was after that excitement that I discovered no spark
from the coil to the distributor. Having an inventory of “good, used”
parts, I swapped out the coils and power modules/amplifiers with
negative results. Then the CPS harness and the ESS harness with the
result of spark to the distributor from the coils but spark to the
plugs only to the B bank, as described above. I WILL take your advice
and revisit the rotor and distributor cap situation. Thanks again!
Michael
Quoting baxtor noreply@jag-lovers.com:
