The Steering is stiff only when going over 13mph. Going around corner at medium speed, steering is stiff, and as soon as the speed drops to 13mph or less it frees up to normal.

Parked it is easy and normal... rev engine parked, steering still easy...

It is related to road speed. Going strait, over 13mph it stiffens up.

Dealer suggested it might be Body Control Module or a sensor or solenoid..

No diagnosis I was just describing it to them...

Anyone have any ideas???

Thank You!

2004 Vanden Plas

 

Do you have the shop manual? It's free on this forum and it's called the JTIS. Or you can get a PDF version on EBay for pretty cheap. I would get one or the other NOW!

If not you will need to take to a dealer.

You will need to troubleshoot the VAPS stuff.
VAPS - Variable Assist Power Steering. This changes the amount of P/S assist based on car speed and how fast you are turning the steering wheel.

I think mechanically you are OK with the rack but the solenoid could be the problem and at least on the S Type the FEM controls the VAPS based on the above inputs. So you could also have a FEM problem or the wiring in-between them.

Have you got under the car and unhooked the VAPS sensor on the rack?
Report back how it drives with it unplugged because the default should be full assist if the VAPS stuff fails.
.
.
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Thank you very very much.. I will post back once I test it..

 

The resistance on the solenoid is 0

I read that one that works should be 7

Default unplugged is hard steering..

I guess it needs voltage to open and make the steering easy..

My question is how to remove just solenoid. Looks like 2 little bolts.

Will fluid leak out if solenoid is removed?

Thank you for your help..

 

There maybe some oil come out as the solenoid will operate a oil control valve so have a container ready but if the steering is ok when standing still it will the solenoid will probably be ok . sounds more like a speed input problem have you tried disconnecting the battery leads and touching the leads together this will reset the ecu's make sure you have your radio code you will need it done this a couple of times on mine when things go wrong spoke to a jag tech awhile ago and this is the first thing he does when one comes in with a electric problem

 

I already tried the hard reset. When I unplug the solenoid the steering is always hard. The resistance is 0 on the solenoid. I think i read online if it was good, it should be 7 ohms.. I don't know for sure... thanks.

 

If I put test leads on the wires going to it, the faster I go the volts should decrease I would think if no volts make it all the hay hard, how does the dealer diagnose this? Check voltage from computor and test the resistance at the solenoid I would think. Can anyone verify this or correct my understanding? Thanks

 

Ok, it's called a transducer. Part #XR830017. Is there a way to rebuild the part. "They" want $517 just for that little part.. is there a way to make the valve think it's parked by supplying the proper voltage. I don't mind running a wire to it from a power supply, to make it work. This car is really out of my price range and I would like to do all the work on it I can.

 

Hi rocknrollteddy,

You can download the six sections of the X350 Workshop Manual from this forum at these links:

http://www.mediafire.com/download/md...f+contents.pdf
http://www.mediafire.com/download/aa...nformation.pdf
http://www.mediafire.com/download/n3...2.+Chassis.pdf
http://www.mediafire.com/download/9b...Powertrain.pdf
http://www.mediafire.com/download/0i...Electrical.pdf
http://www.mediafire.com/download/4j...+and+Paint.pdf


According to the Chassis section of the manual, the X350 uses a "rack and pinion type, variable ratio steering gear with speed proportional servotronic." According to the Jaguar manual, the variable signal from the Generic Electronic Module (GEM) in the Instrument Cluster (IC) is Pulse Width Modulated (PWM). If so, you would not be able to simply hardwire a voltage to the actuator to overcome your malfunction. ZF is the manufacturer of the Servotronic system, and their literature doesn't mention PWM, only that the current to the transducer is varied:

http://www.zf.com/media/media/en/pro...otronic_de.pdf


You can see the Variable Assist Steering Actuator on the schematic on page 75 of the 2004 X350 Electrical Guide, which you can download here:

http://www.jagrepair.com/images/Elec...al%20Guide.pdf


I couldn't find a resistance specification for the actuator/transducer, but I agree with you that a DC resistance of 0 ohms probably indicates a short in the solenoid coil. This assumes you are measuring the resistance across the two terminals of the solenoid with the electrical connector disconnected. According to the schematic, one of the wires going to the solenoid is White and the other is Red with a White tracer line.

If you do need a new actuator, it would be worth finding a dealer of ZF parts, where you may get a slightly less astronomical price than through a Jaguar dealer (the "discounted" price at jaguarmerriamparts.com is $357.81).

You might be able to find ZF's part number for the transducer by searching here:

https://webcat.zf.com/


Cheers,

Don

 

If you have a voltage tester just run two wires from the plug into the car make sure they don't touch the exhaust then connect the voltage tester to the wires and take the car for a test drive then you will see what voltage are getting at the switch when driving this will tell you if its a voltage problem make sure the plug is connected to the rack

 

Thank you very much!

 

Unplugged it is hard steering. It defaults to the high speed position. It looks like the plug let's you reverse the wires. I didnt.



The triangle with the 0 in the middle symbolizes output in the legend. I don't understand. If both are output then is it using ground? Is it 2 variables? Maybe a typo? Unplug sensor an I get default high speed stiff steering. Ohms across 2 sensor pins on mine was 0. Also the connector enables you to reverse the pins. I didnt. Steering works fine below 9 mph.

 

After hard reset, (touching negative to positive with battery unhooked) it was showing this code. I did web lookup and a site said this..

P1000 - Jaguar
Type Powertrain - Manufacturer Controlled DTC - Manufacturer Controlled
Description
Engine control module (ECM) - internal error
Cause
ECM

After driving it for a week, now
It is showing this code now

P1111 - Jaguar
Type Powertrain - Manufacturer Controlled DTC - Manufacturer Controlled
Description
Engine control module (ECM) - internal error
Cause
ECM

I was reading a different thread and I thought they said it was normal. If computor is good, should my 2004 jaguar vanden plas show any code? Thanks.

Also memory seat function only work intermittently and the cruise control has never worked. Thanks.

This is the only jag I have had so I don't know what is normal.

I was thinking of finding the computer or module that runs these things and spraying contact cleaner on the connections.

And the reverse parking backup system works sometimes. Once I just stopped at a red light and it started beeping. The power steering always goes hard at 9 mph and above, and gets easy at 9 mph and lower... always. . though.

 

If it's a simple switch then it does not matter you need to check the voltage at the switch so you know if it's a switch or controller fault sounds like a controller fault as the switch controls a valve in the rack to allow more oil in when going slow and less as the speed rises . So the faster you go less voltage will be put to the switch as I understand it

 

To test the voltage is it voltage across both wires? Does the polarity matter? Also if I get a used ecm can I simply swap it out or does it need programmed ? Thanks

If it's easy to swap ECM I can get used for around $100.

 

rocknrollteddy,

Both wires coming from the Instrument Cluster are outputs because the signal to the Variable Assist Steering Actuator (VASA) is Pulse Width Modulated (a square wave that alternates in polarity and varies in pulse width but with a constant amplitude).

The rectangle with a diagonal line inside the VASA is the symbol for a solenoid (not a switch). The solenoid incorporates an electromagetic coil and a moving valve plunger.

The coil should have some DC resistance, so the fact that you are measuring 0 ohms across the actuator's terminals indicates the coil is shorted. Which raises the question, are you sure you are reading 0 ohms, or is it possible that your meter is reading OL (overload, meaning a very high resistance)?

If your meter is digital and is fast-reacting enough, you may be able to read an AC voltage across the terminals of the wiring harness electrical connector for the actuator. Otherwise you would probably need a scope to see the waveform of the signal.

Cheers,

Don

 

So is there anyway you can measure the signal don love finding out about this stuff

 

It was an analog meter. I thought it was close to 0. Not sure. So basically I cut a little of the side of the insulation on both wires, hook aligator clips to both wires, make sure it is plugged in to the transducer, and the polarity shouldn't matter because it is ac volts? Do I need to check for ac voltage or dv voltage? Then drive and see that the volts decrease as speed increases? Is this correct

 

I don't know if you'll be able to measure the AC voltage with your analog meter, but it would be worth a try if your test leads are long enough to reach from the steering rack to the passenger compartment so you can read the meter while you're driving. I would not cut the insulation - I would just disconnect the electrical connector from the actuator and plug your test leads into the wiring harness connector and tape them in place so they won't fall out while you're driving.

But before you do that, you might check the DC resistance across the actuator's contacts again (with the wiring harness connector unplugged). Confirm that you have 0 ohms. I suspect you should have at least 1 ohm or more.

By the way, in case I forget where I read it, here is the reference to PWM from page 913 of the Chassis section of the X350 Workshop Manual pdf file:

Buzz (Electrical)
A different steering buzz can be caused by pulse width modulated (PWM) electric actuators used in variable assist steering systems. This buzz is felt by turning the ignition key to run without starting the engine and holding onto the steering wheel. In extreme cases, the buzz can be felt with the engine running also.

And from page 917 of the Chassis section:

The vehicle uses a rack and pinion type, variable ratio steering gear with speed proportional servotronic. The power steering pump is belt driven on all model variants and the power steering oil cooler is of a tube and fin type and is mounted to the front of the cooling pack.

A variable steering rack ratio reduces the amount of turns from lock to lock to improve parking maneuvers without loosing any steering feel at higher speeds.

The steering assistance decreases smoothly at a calibrated rate to increase the steering efforts required as vehicle speed increases. The steering efforts are controlled by the actuator position, which in turn is controlled electronically by the speed proportional servotronic curve which is incorporated within the Generic Electronic Module (GEM). Similar language appears on an extra page inserted between pages 7-38 and 7-39 in my copy of the 2004 XJ New Model Introduction Dealer Training Manual.

It is obvious from the schematics in the Electrical Guide that the GEM referred to above must reside within the Instrument Cluster.

To see what a PWM signal looks like, see this post from Cambo, where he scoped the PWM signal to the CATS suspension solenoid. The signal has a frequency of 400Hz at 5 Volts:

https://www.jaguarforums.com/forum/x...76/#post544336

Cheers,

Don

 

Thinking about your actuator, if the coil is truly shorted, it is possible that it could be rewound by a shop that repairs electric motors, assuming they can open the actuator case to remove the coil.

Anyone with knowledge of rewinding electric guitar pickups might also be able to rewind the coil.