These new transmission faults are indicative of a low battery I’ve found, You may get a self.level suspension fail warning as well, these E53s go nuts with even a vaguely low battery! I’d stick the battery on charge overnight before attempting anymore fault diagnosis.

Personally I’d just leave it hooked up to the charger while you work as these 3.0d eat battery voltage when your cycling the ignition. Especially if your cranking it over as well, these diesels have big juicy starters to turn that high compression engine over so they munch battery charge!

Now the fault is persistent have you tried scanning for faults again to see if the car now has fault codes. If not I would continue with replacing the DDE relays, they are cheap from an motor factors and if they don’t sort the issue then you have a bag of spares. Obviously replace them one for one. You can simply remove them and read the code on the top for most, but if your unsure just take them to the shop with you! That’s what I do!

Finding a bad solenoid is a royal pain in the backside, as if it’s intermittent then it’s luck if you catch it when it’s not working, and the slightest knock or touch can cause the coil to energise again and poof your fault with it!! But as you say the fault has now become terminal so the electrical cause should be a lot easier to root out now.

I would start with the battery being charged fully and kept on charge while you work.

Then (as the car won’t start anyway) get someone to cycle the key on and check the relays detailed above. Or as I suggested just sling some new ones in... they are normally only a couple of quid from your local motor factors anyway.

Remember you are listening for an audible “click” from the relay as it energises so if your not sure how to test the old relays with a meter, just use your ear and get someone else to turn the key.

If you are unsure about a relays serviceablity you can also remove it, then use a piece of wire and bridge the “gate” manually. This basicly removes the switching effect of the relay and just makes it permanently “On”. But with this be ABSOLUTLY sure your bridging the right connections!

You can also check for the “trigger/signal” with the relay pulled as well. Using a multimeter stick the positive probe into the signal wire socket and then just pop the negative on some metal or a earth point. Then cycle the key and you would expect to see the 12v appear on the signal wire.

Once you have changed/checked all these relays I would then move to the next point of failure, the pumps.

To check these you have two options,

One use a multimeter and probe the contacts while the key is in the correct position for the pump to be on.

Two remove the connector, use some wire and a 12v battery and force the pump to run.
Option Two would be the undeniable proof that the pumps are working. I have a 12v motorbike battery for testing small Low power components exactly like this. And I just use some appropriate gauge speaker wire to stick into the connector. Obviously..... find out which pin does what first though! Only apply voltage to where it’s designed to go!!! You fry your pump that’s your own fault! (But equally it’s a simple +12v and - GND pump so I’d imagine it would just spin in reverse.)

Following this I would take a small bit of green scotchbrite or V Fine sandpaper and clean the contacts on both pumps connectors and pins if they look even a bit dirty. Same with your relays, if they are new relays you can get a watchmakers flat blade screwdriver and hold some v fine paper around it’s point and gentle clean the relay “socket” contacts. Not too much here just enough to take off any corrosion that may have formed. Again do at your own risk and make sure the keys out when you do it lol.

Now if you find that with option one you don’t have voltage to the pump that now indicates that the wiring is potentially damaged or for what ever reason your DDE is not outputting the correct signal. But these are both highly unlikely without other faults. so I would lead you test all components in the system before testing wiring integrity or looking at the DDE itself.


None of that was supposed to sound patronising btw! I just read in your previous post your not completely Au Fai with electrics! If it sounds rude just tell me to wrap my tits and I will!

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E53 3.0d Sport 119,000 Miles
E61 535d Estate - Hybrid turbos and Dark-side intercooler...389hp,792nm