[xj-s] Speedometer not working and engine cuts out, 89 XJS

XJ-S
1

My speedo works once in awhile, jumps around and then dead. The car
will run with out the speedometer, for awhile. My wife drives the
car in slow traffic. The engine will quit but after a few tries it
starts back up goes fore awhile then dies again.
Kirby says it could be the crank pick up or speed sensor.
Trip computer has been acting funny too.
Not sure which one they mean, speedometer impulse sensor or
speedometer transmitter
What is the differance between the speedometer impulse sensor and
speedometer transmitter?
How can I check the speedometer transducer and how hard is it to
replace? Price of transmitterr $$$ compared to impulse$.
Please let me know . My wife now want me to sell my 89 XSJ. It’s a
sin!!!–
odie
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2

In a message dated 6/16/2006 8:41:39 AM Eastern Daylight Time, “odie” fgon@chevrontexaco.com writes:

My speedo works once in awhile, jumps around and then dead. The car
will run with out the speedometer, for awhile. �My wife drives the
car in slow traffic. �The engine will quit but after a few tries it
starts back up goes fore awhile then dies again…
Trip computer has been acting funny too.
What is the differance between the speedometer impulse sensor and
speedometer transmitter?

Hi Odie:

Regardless of whether you have a Marelli or Lucas ignition, there should be NO connection between the ignition system and the speedometer.

The Speed Transmitter is mounted on the right side of the rear cover of the differential, next to the filler plug. A cable that has a protective rubber spiral around it then runs from the transmitter to the speed interface on the left side of the boot. Signals from the Speed Interface go to the speedo and trip computer, as well as to the Fuel Interface. So a failed Speed Transmitter, or more likely damaged wire running from the Speed Transmitter to the Speed Interface, would NOT affect how the engine runs.

If you have a Marelli car with intermittent shutoff problems, it is possible that either the TDC or Crank Position Sensor at the crankshaft damper, or the Engine Speed Sensor at the flywheel (or their wiring/connectors) could be failing. I don’t have a Marelli car, but there are signal tests with an oscilloscope described in the Service Manual. Like any intermittent problem, testing is only valid during failure to run.

Of course there are numerous other things that could cause an intermittent cutout of the ignition or fuel injection, so the next time it won’t run/start, you need to check for injector click during cranking, HT spark during cranking, and indicate whether you have a Marelli or Lucas ignition.

George Balthrop, Clifton, VA USA
85 & 89 XJ-S Coupes; 89 XJ40 VDP

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3

In reply to a message from odie sent Fri 16 Jun 2006:

Odie, If you have an 89 XJ-S V12 car that has the Marelli ignition
system on it, then you have 3 sensors to look for.
There are 2 sensors on the engine, one at the front at the damper,
this sensor triggers the FI and ign. systems. This is usually the
one that gives problems. Things like the engine cut out.
The other sensor is located at the flywheel, this sensor tells the
ECU that the engine is turning, so the ECU will keep firing the
injectors.
The number 3 sensor is located in the diff, this sensor sends the
signal to the speedo.
Chadbourn Bolles
803 798 3044–
Dr. Chadbourn Bolles
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4

In reply to a message from GBalthropXJS@aol.com sent Fri 16 Jun 2006:

Not to ignore the ‘‘easy stuff’’ again … How old is your battery
and/or how clean & tight are the connections to it. Especially the
ground side of things? Might be worth a check.–
The original message included these comments:

In a message dated 6/16/2006 8:41:39 AM Eastern Daylight Time, ‘‘odie’’ fgon@chevrontexaco.com writes:

My speedo works once in awhile, jumps around and then dead. The car
will run with out the speedometer, for awhile. �My wife drives the
car in slow traffic. �The engine will quit but after a few tries it
Trip computer has been acting funny too.

–
Jamie - 88 SIII V12 VdP & 89 XJS Conv
Tulalip, WA, United States
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
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5

In reply to a message from odie sent Fri 16 Jun 2006:

Thanks for you help. I replaced the 2 engine pick ups. Still have
a problem with the speedometer. I pulled the cluster, clean the
contacts, checked my battery and cleaned my grounds.
Sometimes it works and then dead.
Is there a way I can check the speedometer transmitter? One reply
suggested turning the wheel when jack off the ground. What type of
signal should I be getting, pulse? Worse case! Does anyone know
where I can find a good deal on the speedometer transmitter, P4019-
42747. The best price I found so far is $300. OUCH!–
The original message included these comments:

My speedo works once in awhile, jumps around and then dead. The car
How can I check the speedometer transducer and how hard is it to

–
odie
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
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