Timm's E64 Ambient Temperature Problems - Soft Top Won't Open Either
It's the UK, but surely, it isn't minus 40 degrees Celsius outside?
We're on our way back from the garage where we bought the E64, when all of a sudden we got very hot! The A/C has decided
to fry our faces off and at the same time an exclamation mark appears in the centre of the instrument cluster followed by a
snowflake symbol. Adjusting the A/C temperature cooled us back down again and we made it home happily.
A quick look at the instruments when we got home showed that the car thought the outside temperature was -40C
Not that worrying, a common problem on the E31, E32 and E38 - except they always show -37.5C! But, with the greater integration of all
the electronics in the E63/E64, the failure of the Ambient Temperature Sensor causes more problems - one of them being this:
Yes, the Soft-Top does nothing except illuminate the red LED - and that is very disappointing for a convertible - I'm gutted and really
don't want to be driving the car all the way back to Swindon for the garage to put it right, what a pain. Nah, I'll have a stab at it myself,
at least it will be the first fix in the E64 sections and I've got to start somewhere. The incorrect Ambient Temperature reading is probably
the cause of the Soft-Top doing nothing - if I had the information here I would have been absolutely sure.
A quick look on RealOEM shows that the Ambient Temperature Sensor is right behind the lower grille at the front centre of the car, it
looks like access is made from under the car - so, up on the ramps we go:
As a few people have asked, the wooden thing under the rear wheel is just a length of plywood with a couple of 50mm square lengths of
wood screwed to one end - I run the car up to the start of the ramps, and then stick the wooden device under one of the rear wheels. As
I go up the ramps the wooden device stops the car at the very top of the ramp. There is no chance of popping over the edge or tilting the
ramps as the front wheels reach the end. I've done that before and never want to do it again!
We need to remove the engine under-tray - this is held by a number of 180-degree-turn fasteners. The Ambient Sensor connector can be
seen once the tray is removed - but, what caught my attention was a repair that had been made to the loom that ran to it:
Never trust a loom repair that involves these connector-blocks, they are absolutely useless. They let water in and the cheap metals used
cause corrosion that quickly breaks the circuit - they are rubbish! This joint will need to be soldered and insulated with heat-shrink - the
problem is that this joint is a distance up the loom and it would be better to get to the joint from the front.
The break in the loom is right behind this cover, so, a good pull here removes the cover
And there it is, what a bodge. So, off it came, cut back the wires to find a non-corroded section and get the soldering iron out:
Tin the end of the wires, slide the heatshrink over and then solder the wires together using a lay-joint:
....and then heat up the heatshrink until it fully seals the wires from the elements and, apart from putting the covers back on, you are
done! I am glad to report that the garage I bought the car from was so pleased they paid for 6-months road tax - hooray!
Equipment wire 16/.02
Multicore 60/40 solder
3mm Heatshrink
Soldering Iron (use a temperature-controlled one if possible)
Hot-air gun (or use the side of the soldering iron)
Side-cutters
All done, time for a cup of tea
Equipment used in this article
