2005 (54 plate) intermittent starting issue.

[RLango1406]

Hey helpful folk I hope your all OK,

I'm looking for some advice

I have a 2005 volvo XC90 2.4 auto and I recently had it in for a gearbox flush and major service after the dreaded Transmission service required hoping it would go away, well.... whilst the garage is doing the gearbox flush they lost all communication with the whole car.. After days of fault finding they managed to narrow it down to the rear diff module had completely fried, so they unplugged it and communication came back so the service was completed, (rear diff unit now replaced for brand new part by a volvo specialist) however, I now have a however since picking it up from the service its had a intermittent starting issue.

So basically sometimes it starts sometimes it doesn't. Most likely to start first thing in the morning but after a 15 minute journey to a petrol station or school run.. Will not start. Car turns on everything lights up, cranks but won't fire, other times a few tries getsbit to fire.

The car has two faults showing #1 transmission service required (lock up function slipping or not engaging) #2 anti skid service required (break pressure switch fault) Can these issues cause this starting issue in anyway?

The only giveaway I have noticed is when it's going to fire I have airnah, oil pressure light showing along with emissions system light, however when it's not going to start the only light that stays on is the airbag light.. 9nce the car fires all lights go out as usual.

Any insight or thought process is welcomed as I'm am bemused. I have videos of when it fies and when it doesn't is that helps?

[Neil_]

This probably isn't any help, but have you checked the voltage at the battery? I ask because I know as when the voltage drops it throws an abs code before it will throw a low voltage one. Doesn't make sense with the intermittent starting necessarily but I think good to check the basics first!?

[john langrick]

Hi, I had a similar problem on my old xc70.

I my case when failing to start, but cranking, I also noticed the tachometer never moved when cranking and other lights stayed as yours.

But mine have a clear message and indeed was a lose connection to the crank position sensor.

I can't see how this is likely in your series of events, but worth a try I guess.