[xj-s] Calling all ABS experts

XJ-S
1

Hi again,

Some updates with my ABS light diagnostics:

(1) Read codes via flash sequence. Got 21, 33, and 43.
Code 21 is ‘‘main valve failure.’’ Codes 33 and 43 are right
rear sensor failure.

(2) Checked resistance to both rear ABS wheel speed sensors.
Left rear (no code) was 1.1 ohms. The right rear was all
over the place, confirming what codes 33 and 43 were telling
me - the RR sensor was messed up. Took it off and noticed a
0.25’’ crack in the insulation…

(3) Got a supposedly good used RR sensor and installed it.
When I test it’s resistance I get 0 ohms. QUESTION 1 = Is
that acceptable?

(4) I started the car and there was no ABS light!!! Before
I swapped out the RR sensor I had the ABS light from the
moment the car was started. HOWEVER, when I took it out on
the road, the ABS warning light lit up at 15 mph. I tested
it repeatedly and got the same result - when the car was
started…no light…at 15 mph, the light comes on.

(5) So I re-do the flash/blink test. Same codes 21, 33, 43.

POSSIBLE EXPLANATIONS/QUESTIONS:

(1) I read somewhere in the archives that code 21 is a ‘‘high
priority code.’’ So maybe even though the sensor is fixed,
those codes won’t go away upon activation of the light until
code 21 is resolved…

(2) In another place in the archives I read that sensors
usually cause the light to go on at 15 mph…this would be
in direct contrast to my hypothesis above…

(3) A member was kind enough to send me the manual, but I’m
having trouble understanding it. What would be your next
step to resolve code 21?

Any additional thoughts?

Thanks!–
jstjagguy
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2

In reply to a message from jstjagguy sent Wed 15 May 2013:

Car is a 1995 XJS with the Teves III accumulator system.–
jstjagguy
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3

In reply to a message from jstjagguy sent Wed 15 May 2013:

Did you do the resistance check on the main valve according to the
trouble shooting chart - if so, was it the same (or very near) the
value as given by the chart? If not then you have a bad solenoid
and will have to change that out. If the resistance is correct or
very near then you probably have a stuck or partially blocked main
valve which you may be able to clear.–
lockheed 92 XJS Cpe/97 LT1 Miami FL/ 96 XJS Cv 4.0 Austin TX
Austin, TX, United States
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4

In reply to a message from lockheed sent Wed 15 May 2013:

Thanks for the guidance. For the ‘‘main valve resistance’’
test it says: connect multi-meter to terminals 11 and 18 of
the ECM. Is the ECM the thing in the trunk near the pigtail?

If so, I don’t see any visible terminals. Do I need to get
it out of there somehow or open it up to find the ‘‘terminals?’’

Thanks again!–
jstjagguy
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5

In reply to a message from lockheed sent Wed 15 May 2013:

Also, does the ‘‘solenoid’’ go by a different name? I Googled
it to see possible parts cost but nothing comes up…–
jstjagguy
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6

In reply to a message from jstjagguy sent Wed 15 May 2013:

Ok, I got the ECM out…but where are the ‘‘pins’’ - - - I
only see one plug going into the big silver box…if I
remove the plug the unit will no longer be connected to the
car…in which case I can’t see how my measurements would
have anything to do with the main valve. Help!

Thanks.–
jstjagguy
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7

In reply to a message from jstjagguy sent Wed 15 May 2013:

Ok, I removed the connector from the ECM…I’m assuming I
should test the pins going to the ECM…

The pins aren’t numbered though. What is the numbering
scheme? There are two rows of pins, one shorter and one
longer…–
jstjagguy
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8

In reply to a message from lockheed sent Wed 15 May 2013:

I have similar problem.
Where can I find the trouble shooting chart?
Main valve and solenoid valve are the same part (JML1908)?
Thanks.–
The original message included these comments:

Did you do the resistance check on the main valve according to the
trouble shooting chart - if so, was it the same (or very near) the
value as given by the chart? If not then you have a bad solenoid
and will have to change that out. If the resistance is correct or

–
Paolo 1990 XJS 5.3 12V Convertible
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9

In reply to a message from jstjagguy sent Wed 15 May 2013:

See Figure 1 on page 70-3 and read the first paragraph there. As
it states, all the solenoid valves are located in the module that
attaches to the ‘‘master cylinder’’ assembly. See page 70-4 and
figure 1 to see how the unit with the solenoid valves detaches.
You should also note that there is a socket located on that
detachable module. It is there that you would find the proper pins
to test the solenoids. See test 20 on page 70-15. See the top of
page 70-18 to identify the terminals in the connector at the top of
the module. There are no solenoid valves in the ABS control module
in the trunk.

It is apparent that you have not read and familiarized yourself
with the information in the documentation that I sent you. I can’t
be of much help to you if you do not put some effort into this
yourself. We cannot do the job for you, but we are willing to help
if there is evidence that you are making an effort to read and
familiarize yourself with the information we have provided.–
lockheed 92 XJS Cpe/97 LT1 Miami FL/ 96 XJS Cv 4.0 Austin TX
Austin, TX, United States
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10

In reply to a message from lockheed sent Thu 16 May 2013:

Ooops - Forgive my vent, I need to pay closer attention myself, not
try to do stuff from memory. I’m currently tangled up in some
other events.

You are correct that Test 20 does say pins 11 and 18 of the ECM. No
point in testing the ECM, there are no solenoid valves there. You
really need to test the socket terminals corresponding to ECM pins
11 and 18. But, the electrical schematic shows that the wire from
pin 11 goes to the fluid reservoir, and not the main valve. This
is something one has to watch out with the Jaguar stuff - there are
inaccuracies. Often, the schematics and/or trouble shooting guides
do not keep up with the changes that are incorporated in
production. Actually, you can test right at the main valve at the
brake unit - the valve on the end of what could be called the
master cylinder. There is a 2 pin connector you can pull and test
the solenoid directly. And, if it is faulty, should be relatively
easy to replace, or remove and clean is stuck or clogged.–
lockheed 92 XJS Cpe/97 LT1 Miami FL/ 96 XJS Cv 4.0 Austin TX
Austin, TX, United States
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11

In reply to a message from PaoloFranco sent Thu 16 May 2013:

Paolo,

I would suggest also getting the electrical schematic for your car
from:

http://www.captainjaguarscathouse.com/Electrical_Reference.htm

As you can tell from my ‘‘Oops’’ apology just posted in this ABS
thread, things are not always what they seem to be either with the
trouble shooting guide, or sometimes even the electrical schematics
because they don’t keep up with the changes running changes in
production. The electrical schematic for your '90 will be
different from that of a '95 in many areas.–
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 Thu 16 May 2013:

Hi Lockheed,

No worries, I’m just happy to have someone who knows the
system assisting me…the help is much appreciated.

When I get back to the car I’ll check the resistance at the
two-pin connector you mention. Again, my apologies for
asking the obvious…but the pictures in the documentation
are not very good…the master cylinder is underneath the
fluid reservoir, right? In which case this solenoid is
right under there as well? If I don’t hear from you by this
evening I’ll try to take some pictures which might help this
discussion. Thanks!–
jstjagguy
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13

In reply to a message from jstjagguy sent Thu 16 May 2013:

Hi again Lockheed,

It actually looks like pin 11 goes to the ‘‘valve block’’ …
not the fluid reservoir. Instead, it looks like pin 9 goes
to the fluid reservoir…it’s tough to follow all those lines!

If pin 18 goes to the main valve and pin 11 goes to the
valve block, will the test at the ECM still work? My guess
is that you may have the lines mixed up???

I think I’ll be able to figure out the numbering now with
the electrical schematic, since there are two sets of
‘‘dummy’’ pins that should orient me to the proper numbering
on the unit. Thanks again for all of your help.–
jstjagguy
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14

In reply to a message from jstjagguy sent Thu 16 May 2013:

The Main Valve sticks out from under the of the reservoir at the
front of what would be the Master Cylinder. See page 70-10 and
fig. 1 - the main valve is at the upper left end of what would be
the master cylinder. The valve block to the left contains the
other 6 solenoids and has the 7 terminals depicted page 70-18 at
the upper left (valve block multi-plug). Disconnect the two
terminal plug from the main valve, and test the main valve solenoid
directly without worrying about the wiring to the ECM. If the
solenoid checks good, then think about applying 12v according to
the polarity indicated by the electrical Schematic (pin 2, black
wire is negative) to see if it clicks. If it clicks, it could be
partially stuck or blocked, in which case you would need to remove
it and clean it so it moves freely and will pass fluid when open.
If it won’t click, it could be stuck, or the ABS ECM could have a
failure as indicated in one of the tests.

You can also look at your electrical diagram and see which pins of
the valve block multi-plug correspond to each solenoid. Pin 7 is
ground would be for the ground connection (black wire).–
lockheed 92 XJS Cpe/97 LT1 Miami FL/ 96 XJS Cv 4.0 Austin TX
Austin, TX, United States
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15

In reply to a message from lockheed sent Thu 16 May 2013:

Lockheed,

I tested the resistance at both the main valve plug and the
ECM and got 0 ohms. The manual says I should get between 2
and 5 ohms. So it sounds like I need to remove the main
valve and clean it out?

Are there any instructions on how to do this? It seems like
I would first have to get the brake fluid reservoir out of
the way…and be careful not to contaminate anything…

Also, any clue as to why the new used (apparently good) RR
sensor would be reading 0 ohms? My left one reads 1.1 ohms,
and the manual says both rear sensors should read between
0.8 and 1.4 ohms. With that said, something has changed
since I switched out sensors, since the warning light
doesn’t come on until 15-20 mph, whereas before it would
come on immediately when the car was started.

My main question is how to remove and clean the main valve.
Does the manual describe this anywhere?

Thanks!–
jstjagguy
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16

In reply to a message from jstjagguy sent Thu 16 May 2013:

Justin,

Did you check the resistance between the two pins of the main valve
itself (not the plug)? Just checked mine, it reads 4.3 ohms.

Lets make sure what you are seeing on your multi-meter. Are you
seeing ‘‘0’’ ohms (shorted) or are you seeing and ~ infinite (open).
I’m not sure just how your meter reads out for infinite or open
circuit, but my Fluke reads ‘‘OL’’ (open line) for open circuit
infinite resistance - not to be confused with 0.0 or some value for
a short or good circuit.

Do this: turn your meter to the ohms function and hold the test
leads apart and note what it read for the open circuit/infinite
resistance. Then put the test leads directly together and see that
the reading should be ‘‘0’’ ohms, or some minute resistance
near ‘‘0’’. My fluke reads 0.2 ohms with the leads contacting each
other - the resistance of the test lead wires.

Now, test the two pins on the main valve itself (not the female
plug) and tell me what your get.

If you get ‘‘0’’ ohms (or very near that), then the solenoid coil is
shorted (broken wiring) and is not repairable. If you get Infinite
or extremely high resistance then you have an ‘‘open’’ circuit. In
either case, (if you do not get 2-5 ohms as per the test) you will
need to find a replacement either on E-Bay or places like Coventry
West, Motorcars, Ltd., or similar. They may have good used ones or
be able to get new ones. I don’t know if places like Auto Zone,
Pep Boys, NAPA, or similar will have, or be able to get one for
you. I will see what I can find about R&R the main valve and will
get back to you.–
lockheed 92 XJS Cpe/97 LT1 Miami FL/ 96 XJS Cv 4.0 Austin TX
Austin, TX, United States
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17

In reply to a message from jstjagguy sent Thu 16 May 2013:

''Also, any clue as to why the new used (apparently good) RR

sensor would be reading 0 ohms?’’

Well, apparently the used one you bought is not good - it is
apparently shorted or open. See discussion of the difference in my
previous post. It is possible that you may be selecting the wrong
resistance range on your meter - if that is applicable. What
type/brand of meter do you have?–
lockheed 92 XJS Cpe/97 LT1 Miami FL/ 96 XJS Cv 4.0 Austin TX
Austin, TX, United States
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18

In reply to a message from jstjagguy sent Thu 16 May 2013:

Justin,

I haven’t been able to find any published procedure for removing
the main valve. As I look closely at it installed, I do see a gap
on the left side that would allow access to what appears to be a
snap ring. It may be that prying inward and upward on that snap
ring may allow removal of the snap ring and the main valve. One
would be wise to have a catch pan underneath to catch the fluid
from the reservoir - or remove the assembly before working on it
and drain the brake fluid. Remember, brake fluid is one of the
best paint removers around - be careful.

I did a quick hunt on e-bay to see if I could find the just main
valve - no luck. As I mentioned earlier, you can telephone poll
the various Jag parts vendors like Coventry West, Motorcars Ltd,
etc. to see if you can find any main valves. I suspect not, as
they are not prone to parting one of those units out - more likely
to sell you the whole actuator unit used or new - not cheap.
Hopefully, you will find your main valve will measure the proper
resistance and you will be able to remove it and clean it.–
lockheed 92 XJS Cpe/97 LT1 Miami FL/ 96 XJS Cv 4.0 Austin TX
Austin, TX, United States
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19

In reply to a message from lockheed sent Fri 17 May 2013:

Lockheed,

I turned the meter to the ohms function and held the test
leads apart and got a reading of 1 ohms … then I put the
test leads directly together and got a reading of 0 ohms.
Then I put the test leads on the 2 male pins directly on the
main valve and got a reading of 0 ohms. So it sounds like
the solenoid coil is shorted.

Could you explain the significance of getting a 0 ohm
reading instead of a 2-5 ohm reading in the case of the main
valve or a 0.8-1.4 ohm reading in the case of the RR sensor?
What does the 0 ohm reading tell me from a physical
standpoint (i.e. is there a wire broken…?)?

I called Coventry West and they want $850 for the entire
assembly…as you said, it sounds like they wouldn’t just be
selling me the main valve, but the entire actuator.

I think at this point, the way to proceed is to get a good
RR sensor, install it, and see what happens. It certainly
sounds like the main valve will also need to be replaced;
although I am intrigued by the fact that the light no longer
comes on when the car is started. Instead, it comes on at
15-20 mph. Maybe that is a function of this RR sensor
reading 0 ohms compared to the old sensor reading infinite
resistance.

If the 2nd ‘‘good’’ used sensor doesn’t fix the light, I’ll
order the $850 part and see what it looks like. Hopefully
when I see what I need to replace, it will become more clear
how to proceed in swapping out the units (which may involve
the entire actuator, as you said). Would you happen to have
instructions for swapping out the entire unit?

Please let me know if you have any thoughts about any of this.

Thanks,

Justin–
jstjagguy
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20

In reply to a message from jstjagguy sent Sat 18 May 2013:

Also, I thought the thing with the black ‘‘bulb’’ on the other
side of the engine bay is called the actuator? Is that
correct? If so, what is the name of the ABS main valve +
all the other stuff beneath the fluid reservoir, as it
wouldn’t technically be the actuator, right?–
jstjagguy
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