 | Home > Puma (Tdci) > PUMA Electrical Problems after some rear Chassis welding... |
 
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| RobM Member Since: 06 Jul 2015 Location: Brisbane Posts: 55   
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Guys, Posting this on behalf of a mate...
He had some welding done at the rear of his Defender 130 (2.4ltr Tdci) in regards to some mods to his sway bar setup. The person doing the welding "did" disconnect the "main" battery but wasn't told of the "aux" battery and therefore left it in circuit but it is only used for powering his aux fridges, etc so, in theory it shouldn't have mattered... Upon picking up the his 130 and heading back home the vehicle started doing the following: > Speedo above 40kms/hr started behaving erratically increasing up 18kms/hr above current speed w/o reason (Tacho did not vary at all) > Handbrake Dash light started flickering on/off > Vehicle Engine sometimes surging erratically above 40kms/hr - like when the VCV starts playing up, but he had his replaced 2mths previously Bit of History: The mate did refuel prior to driving the distance to the final destination & it performed faultlessly. Vehicle was performing as per normal before the welding was done... Fuel Filter Checked/cleared OK Ideas/suggestions from anyone would be appreciated... Current diagnosis from mechanics is possible damage to both the Engine ECU and Dash Instrument ECU which will be very expensive if this is the cause... Will using a 2nd hand ECU from a Ford Transit be an option? thanks in advance.... Cheers..... Rob 1995 Defender Tdi 110Wgn 2010 Defender PUMA 110Wgn TRIPS: Meanderingdownunder WikiLoc Trips |
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24th Sep 2019 8:19am |
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| Martin Site Admin Member Since: 02 Apr 2007 Location: Hook Norton Posts: 6605  
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The speedo flickering and power surging may be related.
The instrument pack is directly driven with a speed signal from the speedo transducer, the instrument pack puts the speed out as CAN messages for the engine ECU to use. If the input signal to the instrument pack is faulty, the CAN messages the ECU is reading will be faulty. I would look at the speedo transducer on the rear output housing of the transfer box, swap with a known good one. The handbrake light flickering could also be a low brake fluid level (check this first - and if low then find out why - did welder damage a line/hose?). Otherwise check the handbrake switch and loom for damage/chafing of the wire. Another thought - as the handbrake switch and speedo sensor are in roughly the same place - check around that location for damage/rubbing/chafing of the loom - just in case.  1988 90 Td5 NAS soft top
2015 D90 XS SW |
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24th Sep 2019 9:06am |
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| RobM Member Since: 06 Jul 2015 Location: Brisbane Posts: 55
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Thanks Martin...
I'll pass that onto him to check it out rob Cheers..... Rob 1995 Defender Tdi 110Wgn 2010 Defender PUMA 110Wgn TRIPS: Meanderingdownunder WikiLoc Trips |
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24th Sep 2019 10:41am |
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| RobM Member Since: 06 Jul 2015 Location: Brisbane Posts: 55
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Also, I forgot to mention as well that there was no fault codes up when the mechanic put his diagnostic tool on...
So, would a faulty speed sensor give up any fault codes? Rob Cheers..... Rob 1995 Defender Tdi 110Wgn 2010 Defender PUMA 110Wgn TRIPS: Meanderingdownunder WikiLoc Trips |
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24th Sep 2019 11:00am |
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| Martin Site Admin Member Since: 02 Apr 2007 Location: Hook Norton Posts: 6605
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It may be sending erratic signals but the instrument pack is just displaying the result of those signals. It might do a open/short circuit test but otherwise there may not be other diagnostics available.
The lack of fault codes is in some respects a good sign, but then it's down to old-fashioned head scratching  1988 90 Td5 NAS soft top
2015 D90 XS SW |
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24th Sep 2019 11:12am |
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| RobM Member Since: 06 Jul 2015 Location: Brisbane Posts: 55
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Hey Martin...
Just want to say THANKS AGAIN.... it looks like u were again right on the money.... much appreciated Past on your info to him and yes it looks like the handbrake like was low fluid plus the mechanics have now ordered a new speed transducer as the possible fault. Will keep u posted Cheers.....
Rob 1995 Defender Tdi 110Wgn 2010 Defender PUMA 110Wgn TRIPS: Meanderingdownunder WikiLoc Trips |
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25th Sep 2019 1:14am |
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| RobM Member Since: 06 Jul 2015 Location: Brisbane Posts: 55
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Looks like I may have spoken too soon... Just heard back from the mate and he said the mechanics replaced the speed transducer and the problem is still there. Next thing they are looking at is the Instrument ECU... Cheers.....
Rob 1995 Defender Tdi 110Wgn 2010 Defender PUMA 110Wgn TRIPS: Meanderingdownunder WikiLoc Trips |
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25th Sep 2019 3:40am |
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| Martin Site Admin Member Since: 02 Apr 2007 Location: Hook Norton Posts: 6605
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That's a shame
 1988 90 Td5 NAS soft top
2015 D90 XS SW |
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25th Sep 2019 8:22am |
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| RobM Member Since: 06 Jul 2015 Location: Brisbane Posts: 55
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Martin,
You weren't too far off... the mate just told me that the mechanics found the plastic gears within the Transfer Case that are used by the transducer to measure your speed - apparently the plastic gears were partially stripped. The mechanic removed the backing of the Transfer Case to access these plastic gears and replaced them and all is NOW GOOD according to the mate, so in the end not as bad as it was looking, just mainly labour costs to track down problem... Curious... These plastic gears - if they totally fail totally I wonder what happens to the drivability of the car? Would u still be able to drive it or not?? Cheers..... Rob 1995 Defender Tdi 110Wgn 2010 Defender PUMA 110Wgn TRIPS: Meanderingdownunder WikiLoc Trips |
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25th Sep 2019 8:41am |
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| RobM Member Since: 06 Jul 2015 Location: Brisbane Posts: 55
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Martin,
You weren't too far off... the mate just told me that the mechanics found the plastic gears within the Transfer Case that are used by the transducer to measure your speed - apparently the plastic gears were partially stripped. The mechanic removed the backing of the Transfer Case to access these plastic gears and replaced them and all is NOW GOOD according to the mate, so in the end not as bad as it was looking, just mainly labour costs to track down problem... Curious... These plastic gears - if they totally fail totally I wonder what happens to the drivability of the car? Would u still be able to drive it or not?? Cheers..... Rob 1995 Defender Tdi 110Wgn 2010 Defender PUMA 110Wgn TRIPS: Meanderingdownunder WikiLoc Trips |
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25th Sep 2019 8:41am |
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| Martin Site Admin Member Since: 02 Apr 2007 Location: Hook Norton Posts: 6605
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At least he's not had to throw a load of money at a new ECU or instrument pack
If you lose the vehicle speed sensor/gear then the engine ECU doesn't know the road speed and can't work out the gear. It disables the torque smoothing between gears and makes the drivetrain clunky, but it's still possible to drive. 1988 90 Td5 NAS soft top
2015 D90 XS SWLast edited by Martin on 25th Sep 2019 8:49am. Edited 1 time in total |
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25th Sep 2019 8:44am |
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| RobM Member Since: 06 Jul 2015 Location: Brisbane Posts: 55
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Good to know.... especially when in the middle of no where... Cheers.....
Rob 1995 Defender Tdi 110Wgn 2010 Defender PUMA 110Wgn TRIPS: Meanderingdownunder WikiLoc Trips |
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25th Sep 2019 8:49am |
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