Jaguar XF Unable to Select Gears

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Jaguar XF Unable to Select Gears

Postby Mleese4 » Sat Jun 09, 2012 2:44 pm

Hi All,

This is quite a simple case study but the main reason for me posting this is it shows the power of the scope in comparison to the widely used and in some cases heavily relied upon Multimeter.

This vehicle is a Jaguar XF 3 Litre Diesel

Customers Complaint
Unable to select Gears using the Rotary Shifter and No Gear Illumination on the Rotary Shifter or Instrument Cluster, See Picture attached.
IMG307.jpg
No current Gear Position Illumination and Unable to select Gears


When I got to the vehicle the vehicle would allow Ignition to be operated but the vehicle wouldn't Crank. All other functions of the Rotary Shifter worked, IE General Illumination and the JDO Mode Switches ( Jaguar Drive Optimisation ). This confirmed to me that the Rotary Shifter had the correct Power and Grounds so it was unlikley that this was the route cause.

I connected Canalyser to the Vehicle at the Datalink connector and monitored the High Speed CAN Activity with the vehicle in a Failed state, It was confirmed that the Rotary Shifter was communicating on the HS CAN.

Looking further into the CAN Activity It was identified that the TCM ( Transmission Control Module ) was offline, This confirmed the reason for No Crank and also no Gear Position Illumination. These 2 CAN Messages are transmitted out on the CAN for the PCM to enable the Starter Relay and to the Rotary Shifter and Instrument Cluster to display the current Gear Selection on the Shifter and also in the message centre of the IPC.

So it was back to basics, and started by checking the 2 power feeds to the TCM directly at the TCM with the Ignition on. 1 Feed is Ignition ( Blue Trace ) and the other is permanent Battery power ( Red Trace ).

TCM Power supplies.bmp
TCM Power Supplies, ( Blue is Ignition and Red is Permanent)


Previously these Power supplies had been checked using only a multimeter and they were deemed to be acceptable, However the Pico tells a different story.

The Route cause of the Power Suppy Issue turned out to be an Intermidiate connector full of water which had corroded the Terminal for this feed in the connector.

This just goes to show how much more information can be gained from using the PICO instead of a standard multimeter during diagnostics, the multimeter check had deemed the power supplies to be accetable when clearly they weren't. The Scope had just prrevented a brand new TCM being fitted to the vehicle at the cost of approx £1500.
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Re: Jaguar XF Unable to Select Gears

Postby Robski » Sat Jun 09, 2012 7:21 pm

I couldn't agree more about the power of Pico scope................but what about a simple load test which would have brought the DMM back into play ?
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Re: Jaguar XF Unable to Select Gears

Postby GRUSS » Sun Jun 10, 2012 1:25 pm

Nice little case study, had a very similar issue with a BCM on a Astra j. I use loadpro leads with my DMM, the more I use them the more I like. They've really helped me out.

http://www.aeswave.com/products/Product.asp?i=1087

Got mine from technical topics but can be sourced else where. :D
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Re: Jaguar XF Unable to Select Gears

Postby Mleese4 » Sun Jun 10, 2012 3:45 pm

Hi Gruss,

Thanks, I think I might go and buy some of these leads they look pretty good and to be honest they wont be short of use either :D
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Re: Jaguar XF Unable to Select Gears

Postby GRUSS » Sun Jun 10, 2012 8:11 pm

Mleese4 wrote:Hi Gruss,

Thanks, I think I might go and buy some of these leads they look pretty good and to be honest they wont be short of use either :D



Yeah they are really good. So far they've helped me out with the following problems...

Corroded power feed to a door window motor on a insignia
Corroded block connector for power feed to a Astra j BCM
Kia sportage heater resistor pack ( bad earth which was shown up in minutes)

I also use them in conjunction with my power probe ( cheap universal one). Can also show up opens and shorts but you've probably seen that in the YouTube videos.
Take a little time to get used to using them and how they work but yeah best thing I've bought in a long time.... Oh and as well as the pico! :D
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Re: Jaguar XF Unable to Select Gears

Postby Kev » Tue Jun 12, 2012 8:55 pm

Hi Mike,
Thanks for the post! Out of interest did this vehicle not also log a fault code in the engine ECU/PCM to the effect that the transmission was offline? The other interesting point is that you have approx five volts on the red trace which you describe as a permanent feed, I take it that this should have been a 12 volt feed in! I'm quite sure that the pico scope is of a very high impedance just like a digital multimeter, so wouldn't that have made the multimeter capable of showing the reduced voltage value also? . . . Just interested!

Thanks again for posting Kev
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