QP6 GTS strange fault

[JontyUAE]

Hello all,
Last few days a strange happening with my car, actually bloody dangerous.

Was on the freeway yesterday and at circa 135kmh and the car just completely cut out. I think it started with an anti lock brake service request but then just went into shutdown. it`s done it a few times last week (always starting with a service anti lock brakes warning, then suspension fault then auto gearbox fault) but never on the freeway. The closeness with which Nissan Patrols and Toyota Landcruisers follow up your a*se here it was very dangerous. Loss of power steering and brake servo was not fun, managed to coax her to the side of the road and shut down and restarted and all fine again.

Car is now with garage here in Dubai. I originally thought dirty wheel speed sensor or some such but that wouldn`t shut the car down like that surely?

Here`s hoping for an easy cheap outcome

 

[conaero]

That is scary.

I would start with the simple stuff, for a car to power down like that suggests a total loss of power. The battery terminals and the battery itself and then if good an alternator test, then you move forward from there.

We regularly get owners reporting that the car feels like its cutting out at speed only for a second and this is the battery not connected tightly.

 

[CatmanV2]

I had an Alfa 75 that exhibited similar symptoms (barring the sophistication of the error messages). Turned out to be a dodgy connection to the fuel pump. Scary as **** losing everything at 70+ Having two tyres go was easier.

C

 

[JontyUAE]

I`m hoping its a loose connection, I might add though that the dashboard lights and dash stay powered up so doubt it`s battery although I have heard that the QP can be sensitive to battery voltage. Let`s see what the garage come back with. I`m hoping its stored a code and not just cleared the fault each time on re start.

 

[JontyUAE]

Garage are saying that connection to the ECU was lost so they are cleaning and lubricating connectors. Funnily enough the garage is just round the corner from my office and just as i got in cab home my car came past with test driver giving it a little right foot. Car sounds soon good from the outside.

 

[CatmanV2]

Garage are saying that connection to the ECU was lost so they are cleaning and lubricating connectors. Funnily enough the garage is just round the corner from my office and just as i got in cab home my car came past with test driver giving it a little right foot. Car sounds soon good from the outside.

They're all like that, sir

C

 

[JontyUAE]

Well I got the car back last night. First thing I noticed driving it off the transporter and something I forgot to mention is that it seems to be taking a good few seconds of cranking to start. It`s been doing that for a few weeks. I kinda put it down to the UAE Summer but now I think the two issues are related. Suffice to say I drove the car into work this morning and it cut out again. Same warnings, Service ABS, Suspension control failure, park assist service required. Again it was fine after a restart. Off it goes back again.

 

[Phil H]

If you've checked the battery state and connections as Conaero suggested, I'd be looking at earth connections.

 

[Gazcw]

Had similar with a BM X5. It was a faulty alternator. Not enough power for all the systems it is trying to run.

 

[CatmanV2]

Had similar with a BM X5. It was a faulty alternator. Not enough power for all the systems it is trying to run.

Odd. I'd have thought that nearly everything (well everything, really) while cranking comes from the battery. I'd always thought that the alternator did nothing until up to some sensible revs.

C

 

[conaero]

Alternator likely. Connect a volt meter across the battery. Start the car, you should get 13.7 volts falling to 13.3 as it warms up. Anything 12.x or lower or higher then it’s the diode pack on the alternator.

Could also be the crank or cam sensors breaking up and loosing synchronisation and cutting the power.

If it does look like the altenator TURN THE POWER OFF BY DISCONNECTING THE BATTERY NEGATIVE we have seen them spontaneously smoke and go up with the car off and the keys removed.

 

[Scaf]

Odd. I'd have thought that nearly everything (well everything, really) while cranking comes from the battery. I'd always thought that the alternator did nothing until up to some sensible revs.

C

True, but a faulty alternator will mean the battery won’t be fully charged or has been overcharged and is knackered, so giving the symptom of poor cranking.

 

[CatmanV2]

True, but a faulty alternator will mean the battery won’t be fully charged or has been overcharged and is knackered, so giving the symptom of poor cranking.

Ahh, thanks! Makes sense

C

 

[JontyUAE]

Still no update, i had the car back and i havent taken it back in yet. On average does it once per trip. Let me down at a very busy intersection by Arabian Ranches in Dubai today, very embarrassing, lots of beeping behind me.

Will get recovery truck to collect.

 

[JontyUAE]

Ok, quick update. Not good news. My garage have sent the car back as they are unable to determine the fault. Checked all the normal variables that were mentioned.

All they have said is that the ECU is de energizing. Thats probably a bad translation of power is being interrupted to ECU.

They said they dont have an auto electrician on staff currently and they would also need a wiring diagram.

Its going to a different garage on Monday who has a weird fault guru who works on a lot of high end cars here in UAE.

Intermittent faults are the worst to diagnose.

 

[philw696]

Ok, quick update. Not good news. My garage have sent the car back as they are unable to determine the fault. Checked all the normal variables that were mentioned.

All they have said is that the ECU is de energizing. Thats probably a bad translation of power is being interrupted to ECU.

They said they dont have an auto electrician on staff currently and they would also need a wiring diagram.

Its going to a different garage on Monday who has a weird fault guru who works on a lot of high end cars here in UAE.

Intermittent faults are the worst to diagnose.

Good Luck and totally agree intermittent faults are a nightmare and I've been a mechanic for 45 years you can certainly spend some time tracing electronics.
A Good auto electrician is worth his weight in Gold but getting rarer by the day as youngsters don't want to get into that part of the Automotive profession anymore.

 

[JontyUAE]

Car has been at another garage here and they are saying engine ECU and body control module need replacing.
Im finding that pretty hard to believe that both modules fail intermittently at the same time.
Pretty gutting if it is that. Not even sure if the engine ECU is available and probably exorbitantly expensive for both anyway.

Unfortunately skill levels here mean the mentality is throw new parts at problem and see if it fixes it.

 

[philw696]

Car has been at another garage here and they are saying engine ECU and body control module need replacing.
Im finding that pretty hard to believe that both modules fail intermittently at the same time.
Pretty gutting if it is that. Not even sure if the engine ECU is available and probably exorbitantly expensive for both anyway.

Unfortunately skill levels here mean the mentality is throw new parts at problem and see if it fixes it.

Has it had a flat battery and been jump started by any chance ?

 

[JontyUAE]

Not in the 4+ years ive owned it.

 

[philw696]

Not in the 4+ years ive owned it.

Very strange then that two control units just die from my experience.
When at the Dealership working I've seen Sales Guys blow units from jump starting a car incorrectly.