Monday, March 11, 2013

When Range Rover air suspensions go flat




Last week we received a 2005 Range Rover for service.  It had two observable symptoms – the suspension would go flat, and the suspension warning light was on.  We scanned the car using the Land Rover test system, and read several faults.

We got a long time to charge suspension fault, a rear height sensor fault, and a low voltage fault.  That’s when things got complicated.  The car obviously had multiple issues. What now?

When you see a long time to charge fault in a six year old Range Rover, it usually means the compressor is worn out.  The question is – why?  Compressors on these trucks wear out on their own, but they also wear out because of leakage (it overworks them and kills them even quicker.) As a service person we have no way to know what’s happening.  We have to change the compressor and see what happens.

Unfortunately, it wasn’t a simple one step fix.  The compressor contains electronics, and it has different running parameters from the original unit.  We didn’t discover that until we opened the replacement part. Carmakers do that – they supersede parts without warning, and we service people just have to roll with it.  We installed the compressor, and got a new fault.  After a call to LR Tech Support, we learned that new software was needed in the controller, but the controller might not be compatible. 

 That took us to the second problem – the battery voltage.  Software programming is a power-intensive process.  That’s why you always have to have your laptop connected to AC power when doing an update.  For the car, we need a strong battery.  So we proceeded to change it. It's very common for a car with a single issue in the customer's eyes to have multiple underlying causes.

With a good battery in place we did the software download – and presto – Nothing!  Another call to techline confirmed the original suggestion – not all control units accept the new update.  The solution – a car-wide update, which we are waiting to receive and load.

If that cures the problem, we are done with this step.  If it doesn’t, the car will need a new suspension controller as well – one that runs the latest software and controls the new compressor – which is the ONLY compressor they now sell.  This is truly a situation where additional layers of troubleshooting and repair reveal themselves as we go.

Once this situation is resolved, we still have to solve the height sensor problem.  Once again, it’s a step by step thing.  A new sensor may be the answer, but the sensor fault may be an artifact of something larger – leakage from an airbag, or even intermittent connections from a corroded wire harness.  When a car is 5-6-7 years old, anything is possible.

What’s the takeaway message from this story?  Don’t ever ask “How bad can it be?” because even a simple seeming problem can expand or resist resolution for a long, long time with the complexity of today’s cars.  All we can know is what the fault codes tell us. Owners believe they point straight to an answer, but they seldom do.  More often than not, the codes reveal multiple problems, and the solutions – as seen on this truck – may themselves be sequential processes.  There is no way for us to know what it will take to reach the endpoint – a fixed car – until we are there.

That is the unfortunate reality of computerized automobiles.

We tend to see a lot of situations like that at Robison Service, because our reputation causes motorists to see us as the shop of last resort.  We often get the cars no one can fix, and I’ve yet to have one of these vehicle beat us.  But they can be challenging, to be sure.

Have you got a problem you can't solve, on a Land Rover, Range Rover, BMW, Mercedes, or Jaguar? GIve us a call at 413-785-1665 or find us online at www.robisonservice.com

John Robison