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Fixing my stupid diagnostics with whacky repairs on my grab bag XC90

A mid-size luxury crossover SUV, the Volvo XC90 made its debut in 2002 at the Detroit Motor Show. Recognized for its safety, practicality, and comfort, the XC90 is a popular vehicle around the world. The XC90 proved to be very popular, and very good for Volvo's sales numbers, since its introduction in model year 2003 (North America). P2 platform.
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npexcept
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Year and Model: XC90 I D5 (275) 2003
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Fixing my stupid diagnostics with whacky repairs on my grab bag XC90

Post by npexcept »

More stories from my grab bag XC90 (2003 D5 AWD D5244T);

Just a week before my general inspection (TÜV here in germany) was due, the ABS light came on.
Reading the error codes with VIDA, it did show "BCM-0139 Pre-pressure valve power brake booster signal outside permitted range".
The car was standing at that time so I really did wonder why it just broke. The days before were pretty cold below freezing, so that may had something to do with it I thought. First I checked all connectors (well not all, my stupid a** simply did not check the big one on the BCM below the front fuse box...)

So it must be the pre-pressure valve I thought. Infos about this are super rare, even in vida! The only info I found were a sentence in the brake booster article!
Since this valve cant be purchased alone, you have to buy a new brake booster (the valve seems to be glued/pressed in there).
I ordered a new brake booster, installed it, and - error persists - slight panic.
(I also installed 2 new brake pressure sensors, these on the master brake cylinder, damn they pricey)

Finally I checked the BCM. All connectors in this car did look good, so I didnt really expect something bad on the BCM.
Well, thats the thing with cars without a clear history... some dipsh*t did very likely pressure wash the inside, flooding the BCM connector (its only splash resistant from the underside!). With below freezing, something finally broke in there. One of the pins on the BCM unit corroded and broke of. panic.
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I ordered a new used BCM to replace, but after installing it and finding out, that you have to program these (which is how i read not possible with the 'offline' vida), I returned it. So lets not talk about that approach :D

From this thread viewtopic.php?f=9&p=475693 and seeing the inside of the BCM, i wondered if i could simply route a single wire to the outside of the module. So i did that.

I cut it open above the broken pin with a dremel and soldered a new wire to it.
On top a 3d printed cableguide flooded with glue to keep it watertight.
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So yeah, finally all the errors are gone and the car is ready for inspection.
I see this odyssey in a positive way. On this car literally anything can be (relatively cost efficiently) fixed. And with the dodgy history, replacing core components aint that bad of an idea :D

What are your repair stories?
Last edited by npexcept on 27 Jan 2024, 02:23, edited 1 time in total.
Just because you're trash, doesn't mean you can't do great things.
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ggleavitt
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Year and Model: 06,08 XC90 V8
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Post by ggleavitt »

Excellent troubleshooting and a very creative "fix", very much appreciate the post.
2006 V8 Ocean Race #740/800 200k, 2008 V8 Sport 183k

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