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Td5 electrical black magic....


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D2 manual air suspension and ACE. No volumetric alarm installed and immobiliser by-passed (no flashing red light ever) with Webasto night heater but no controller.

When all switched off there is a 450mA discharge at the battery, which is more than just the clock!

The MAF sensor is always warm, so I disconnected the 3 pin socket and measured the voltages (avometer)

1 - 2  0 V

1 - 3  0.5V dithering

2 - 3  7.0V stable

Any ideas from the Td5 ecu experts most welcome........

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Could we have a bit more information?

I'm guessing the original fault you were trying to address was a flat battery? 

Apart from the MAF, what else have you done to track down the drain?

Were the voltages measued across the MAF with the ignition on or off?

Personally, I would unplug the main ECU first.  If there is still a significant drain, it has nothing to do with anything switched by the ECU.  Then you need to start pulling fuses to see which circuit is drawing power.

While I'm not a Td5 ECU 'expert' - I do have a record of diagnosing problems through a logical process of elimination.

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With the ignition off you should have no voltage at the MAF as it is fed by the main relay, not directly from the battery.

The SLABS ECU does stay awake for a few mintues after locking to allow for self levelling. So make sure you give it enough time. If you still have a drain, pull the fuses that are permanently live one by one until the drain disappears. That will narrow it down.

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History....basically a tidy runner, 150K kms. but the last owner apparently used it as a camp site tug and for playing in sand /mud.

I have only driven it 5kms on a track to compare it to mine,  before it gets a complete check over and sets off for for its next 100K kms.

I imagine the last owner completely removed the immobiliser.  If you leave the remote control fob away from the vehicle and turn the key it starts.

My tests were done with the key on the dashboard.

No flat battery...just me looking around to what problems there are before they happen if possible .

I will have some RAVE electrical bedtime reading to do find out how everything ties together, RRC diesels are much simpler but apparently I ought to move into a more modern world.

I will try to give some updates if and when progress is made.

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The plot thickens......

One of the main relays (R9)  was bridged permanently.  When replaced with a relay the 450mA drain became 20mA which seems correct, then there is no fuel pump running when you try to start on the key and the red high temp warning light stays on when all the others are extinguished. Put the bridge back and it starts and runs no warning lights.

This is a German market vehicle and the fuse and relay allocations seem to be slightly different to the French and English. I have  running and  dead french vehicles to compare .

Anyone have any german documentation  links?

I think I am starting at page 1 of the rave electrical to see what has been done to the original wiring............

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