I have a 2004 S-Type with the rear park assist that is presently not working. I've done a look at the various posts on this site and tried the suggested ideas for checking the rear sensor modules in the bumper but I don't hear any clicking when the vehicle is in reverse - I'm making the assumption that it's highly unlikely that all four sensors would be defective. This suggests to me that it is the module at fault (if it was the piezo speaker then I'm assuming that I should still hear the clicking). The module part number is 2R83-15K866-AC. I've taken apart the module but there is nothing obviously wrong with it - I can't see any burn marks or exploded capacitors (most of the components are surface mount components) - maybe one of the ic's is fried but I can't check that. I've checked the 5 amp fuse in the passenger compartment and it's fine. Any other suggestions or things that I can check before replacing the module (I understand that it's quite expensive from the Jag dealer and there aren't any used ones that I can find on the web right now). Thanks for any help.

 

No suggestions on anything else I can try? I guess my next step is to replace the module and see it that works.

 

Chances are you have water damage to the rear park aid assist module. They tend to fill up with condensation and short out the module. Inpsect the module for water damage and also inspect the connector for corrosion.
Goodluck

myglimk2

 

Before I try replacing the module, if it is defective should it generate a code - I scanned the car using an OBD scanner and the only code it pulled was P1111. Any thoughts?

 

I might be able to help here. (Ex electronics engineer). Have your module you think faulty hooked up and working but in such a way you can get your hands on it. In the surface-mount part there's probably a number of small chips. These look like little black or grey squares with lots of tiny connectors along each edge. Modern s/m chips are abt. a quarter the size of a postage stamp. Now put your finger end on each one in turn, and you may find one that almost burns your finger. If you do, you're in luck. The chip has a short. Now don't try and mend it yourself. Find an electronics man and ask if he can replace the chip. Again, if you're in luck it will be a 'common' chip, not a special fabricated for that job. The type number is printed on top. If it's a common chip, it'll cost buttons. The art and expertise is in getting out the dud chip without damaging the print so the new one can be soldered in (with flux and a tiny heat-gun). For a job like that I'd charge a tenner plus the chip.
Now IF there are no hot chips(!), it's possible you have corrosion damage to the print due to water (and it's never just water, there's always something acidic or chemical in it); the same electronics man could help here too. I am of course assuming this p.c.b. is easily removed by being on plugs.
Leedsman.

 

Just thought, not being able to hear the piezo speaker clicking doesn't mean what you think. Connect any piezo tweeter across it and see!
Leedsman again.

 

Thanks Leedsman for your reply - I've taken the module apart and attached a picture. From what I can tell none of the components are damaged/burned/loose. There are no signs of corrosion and my trunk doesn't look like there was any water intrusion (there is a drain plug behind the spare tire which is clear and not blocked). The problem is that I'm not sure if it is the module - perhaps all four of my sensors are defective.

 

I'll try the speaker next - see if that's working. Thanks

 

I've checked your pix. (good photography by the way) and the big chip, the microprocessor, looks like a special. The 16pin DIL chips (Dual In Line) are the ones likely to have the short and be v. hot. There's more you can do. Check the S.M. resistors. These are the little black things about 2mm long with silver ends where they're att. to the print with solder. There will be a number printed on each in white. The number shows the resistance value. Examine each one with a powerful magnifying glass for a tiny burnt spot where the number is. If you find one, take it to your electronics man to be replaced. The burnout is caused by a high-current 'spike' getting into the board from outside. Another thing you can do is to arrange a bright light behind the print while you examine it for cracks with the magnifying glass. Yours looks like glassfibre print. The board is a bit more repairable if the components are on one side only. Again, if you find a crack, get your electronics man to fix it.
Leedsman.

 

Thanks for the advice - will give me something else to explore. Do you know of any way to check the sensors, e.g. take a resistance reading of the wires in the harness at the point of entrance into the module. I've got a schematic from the Service Manual CD and I believe that I should be able to identy by wire colour which set of connectors represent which sensors. I'm assuming there should be a similar resistance reading for each of the sensors and whether one or more are an open short (I may test the piezo tweeter that way as well rather than take the rear shelf apart to get at it - if I apply a small dc voltage to the leads of the piezo tweeter in the wiring harness entering the module I should be able to get a sound out of it I believe).

 

Believe me, the likelihood of all four sensors (if four there be) going faulty at the same time is about as likely as winning the national lottery.
NO! about the piezo! A piezoelectric sounder/tweeter is in fact a capacitor where the dielectric changes shape slightly when stressed by a voltage such as 12volt. It's a thin ceramic plate about the size and thickness of a large coin. Front and back faces are metallized and the two connector wires are soldered to this metallization. In a tweeter it's the same but a little paper cone is glued to the centre. Often, the connector wires get detatched from the metallization if there is a lot of vibration, or they're cheap. If you connect a 12volt battery across one it will click ONCE and then refuse to make a sound until you reverse the polarity. Only AC voltage will make a continuous sound. So drive it with the output from an audio amplifier and it should squawk away nicely. They draw practically no power from the amp. I do hope the sounders in fact ARE piezoelectric, mine sounds to me like an ordinary moving coil speaker.
Incidentally... The piezoelectric effect is used in the latest diesel injectors by Siemens. If you have a diesel S-type, then you have six of them. They should be more reliable than the solenoid type used in earlier engines. A long "stack" of ceramic piezodiscs in the injector have a high-ish voltage applied across them from the logic controller resposible for injection control. The "stack" (a few cm. long and abt. 1cm dia.) expands slightly but with colossal force, allowing the fuel into the jet via an hydraulic amplifier. It's VERY fast because there is no inertia effect as with the electric-solenoid type. Fast enough to have FIVE squirts per power-stroke against the three of solenoids. It's the ideal situation, no moving parts. But I digress...
Leedsman.

 

Hi,
My park assist was not working on my 03 XJR when I picked it up a couple years ago.

Try the following:
1. verify that the left rear backup light works when you put the car in reverse.
2. Follow the ribbon cable that leads from the park assist module to the individual sensors. My ribbon cable was pinched between the steel body and the plastic trunk lining. It had pinched through the insulation on the cable and was shorting to ground. Once freed the system worked fine.

The P1111 code is nothing to worry about. (from JTIS 2003 S-type)

"If DTC P1111 is flagged after DTCs have been cleared, all engine management OBD diagnostic monitor drive cycles HAVE BEEN COMPLETED."

 

Thanks Leedsman and AlleyCat for the advice. My rear backup lights are working properly and following the cable from the Park Assist is difficult because it joins up with a major wiring harness and is tightly bundled. It's hard to check the wiring as it goes to the sensors on the S-type without removing the bumper covers which I'm not prepared to do right now. I can reach the one sensor that is over the left rear exhaust and it feels that it is connected okay.

Thanks for the info on the P1111 code - I've googled the code and downloaded the drive cycle required to clear the code (that's a task for another day!).

I agree with you Leedsman that the odds of all four sensors being defective is low which leads me to believe that it is the module or the piezo speaker. Thanks for the info on the speaker, I would have just connected a 12 volt source and expected it to make a sound but I will rig up an amplifier to use.

 

Okay I've determined that my piezo speaker isn't working - I managed to take it out by moving the rear parcel shelf out of the way enough to pull the speaker out - it was held in by two push pins (what a pain in the you know what to get the shelf partially out - couldn't get it all the way out because of the rear sunscreen, didn't want to force it and damage anything and make matters worse). In the process lost one of the a white plastic plugs in one of the C-pillars and broke a metal tang on the bottom of one of the rear seat bolsters - hopefully it doesn't do anything useful). Once out I applied some ac voltage to the speaker and it was dead quiet - now to call the dealer and order a new one. Thanks to those who replied for your help.

 

Good work EDL, keep fingers crossed now and see if all's well that ends well!
Leedsman.

 

There's just one thing in the back of my mind that's been ****ling away at me. That piezosounder which appears to be duff MIGHT just might be one of those with a fabricated microcircuit actually on the piezoelement itself -- like the ones in those jokey Xmas cards which play a tune when opened. If you can, strip the sounder down and have a look. If it has a circuit, it'll just seem like a black hard plastic "blob" on one side of the ceramic element. If the unit has three wires to it instead of two, it'll be two for power, one for activation.
Leedsman.

 

Thanks Leedsman for the tip - I took it apart and this is what it looks like inside.

 

Point noted EDL. Therefore if there are only TWO wires to the device, putting 12volt on it should logically operate it, since all the pcb you photographed can do is switch the power to the sounder on and off.
Leedsman.

 

Replaced the piezo speaker today ($47 from the local Jag dealer) and everything works fine! Thanks to Leedsman and Alleycat for your help.

 

I hope this thread still has some life...

Speaker is bad, no sound - no continuity when putting a meter across the speaker leads. Sensors (I have rear only) click when sensing a nearby object.

(An aside about getting access to the speaker: I did it by folding down rear seat, crawling upside down into trunk, looking up at the steel rear shelf decking, undoing a sound deadening blank covering up an unused hole for additional speaker. The Park Aid speaker is right there, held in place by plastic compression pegs.)

First, I tried RadioShack buzzers to see what they would do. One sounded when appropriate but gave a high pitched screaming at very low lever when trans was in DRIVE. That drove me nuts. Another, different specs, sounds the beep, but at a very low volume. Not useful with radio on.

I put a voltmeter across the speaker leads and got a 10v +/- reading when the trans was in DRIVE??? I got a slightly higher reading with small greater pulses when the trans was in REVERSE and an object near one of the sensors. Does that mean anything?

Before I shell out either $50 for a new oem speaker OR $500 for a new module and speaker I would like to know if the Module is defective. Should there really be a voltage across the speaker leads when the device is not in an active mode, ie DRIVE not REVERSE and sensing an object?

Or, if the Module is at fault, will the problem show up in a code?

Thanks