*Also posted on the T5 forum*

I could have sworn i had already posted this question, but apparently not, so you wont have answered it.

I was driving along the M5 the other night, midnight, Bristol to Exeter, when i looked down and saw all the gauges were sat on 0.
maybe i looked down because the power died, maybe it died as i looked down. Long story short the van was OFF at 70mph. Engine turning on the momentum of the van.

Hazards on, heavy steering, wooly brakes, onto the hard shoulder.

Turned over but wouldnt start. Sounds like a Body systems computer fuse has gone.
Checked all the fuses in cab, all ok.
Checked all the fuses under the bonnet (Christ i was cold), All ok
Checked all the fuses in the cab again.
Humph

Last thing to try. Everything off. lights, radio satnav, even the hazards. and gave it another go. It JUST kicked over.
Ran home with the radio and sat nav off.

I put a multmeter across the battery later on. 12.3V on the battery, 14.5V with the engine idling. Surely that suggests the alternator is ok??

The ONLY thing i can think it was, was the combination of the heater, lights, stereo and satnav all on at the same time drawing enough power to cause the computer to reboot?

Its been ok since, but ive not driven at night, and not needed my sat nav.

Anyone had anything similar? any thoughts?

2004 2.5L engine.

The time of year when dying batteries get found out.
It’s what my money would be on. There is a realatively big demand for power on modern fly by wire vehicles.
My missus Renault battery dying caused these exact things about six weeks back. New battery solved it.
Similar issue with my T4 a few years ago. All appeared ok until I needed lights and wipers, then it just wouldn’t play ball.
I could be wrong of course.

12.3 on the battery sounds low to me for a car thats been in use……

Our T5 did this after a service apart from the steering lock came on 😯
Thankfully not going that fast and I was in a deserted contraflow so only crashed through the cones into an empty bit of road before stopping!

The problem – some numpty at the garage forgot to do the nuts up on the battery terminal so one popped off – there were a few strong words…

What trail rat says, 12.3v sounds very low. Caveat, my experience is limited to small cars and motorbikes but they’ve all needed at least 12.7v to start, even 12.6v makes the starter motor sluggish and anything less than that is *usually* just a solenoid click.

12.3v is less than 50% charged. Change it. Alternator is healthy though.

Might not be the source of the issue though…as you can see, when running the alternator is keeping the voltage up and it will be rated to cope with all the loads you can reasonably draw.

Did you put the clutch down? As long as you have enough momentum to reach the hard shoulder, leave it in gear and don’t touch the clutch, the engine turning over will still be running the auxiliary pumps such as power steering.

MysteryMove, that sounds scary and wrong…did you try and restart it before the lock came on? Even if you did, the steering lock shouldn’t engage unless you actually pull the key out of the barrel. Its mechanical so electrical issues shouldn’t matter I hope?!

Worst case scenario check. Can you get someone to plug into the engine management system and check for faults? My bora did similar a few times, went into limp mode, died etc then drove fine. Turns out the black box was knacked, garage had never seen so many fault codes on a car that was driven in.

But on the positive side battery seems low.

Further investigation required. Consider that fully charged your battery should be showing 12.7 volts…fully discharged is only a volt less. The voltage will definitely read higher after it’s been on charge (surface charge)IE 13.7 this is normal.

12.3V after the battery has been on charge with the vehicle running indicates either the battery is defective or the alternator is’nt charging it……or both. The alternator will be designed to run everything & charge the battery at the same time during normal running.

If the battery is a handfull of years old it might be worth having at tested. Any Quickfit will have a battery tester. It’ll give you a printout of the battery’s health. It’ll calculate the “cold cranking amps” CCA’s and print you out a wee ticket. Probably in this case telling you the battery is effed due to age & a rise in the internal resistance.

If you replace the battery with a new one check the voltages again with the engine off & then again with it running. At this point you’ll know if the alternator is also on its way south.

D.

Go to tyre / battery place and get them to load test the battery (usually done for free)

this after a service apart from the steering lock came on

That will be because you pulled the key out. Steering lock is a piece of metal that engages and disengages when the key is removed/inserted, nothing to do with the battery.

Power issue so battery, alternator etc.

My T4 has just lost an alternator mounting bolt, belts started making loads of noise and battery light came on as only charging partially.

That will be because you pulled the key out. Steering lock is a piece of metal that engages and disengages when the key is removed/inserted, nothing to do with the battery.

Or it could just be the load from the steering without the PAS pump running. I know when my engine lunched itself the first indication was that the steering got really really really heavy, two handed heave to get it into a layby. And that was only a car.

Or it could just be the load from the steering without the PAS pump running. I know when my engine lunched itself the first indication was that the steering got really really really heavy, two handed heave to get it into a layby. And that was only a car.

+1, modern cars with the PAS failed may as well be locked. Same with the brakes, in theory if the servo fails you’ve got just as much power, in reality you don’t stand a chance.

No idea if it applies, but would electric rather than hydraulic power steering give more of those symptoms (it would die with the engine rather than keep working as long as the car’s moving)?

I put a multmeter across the battery later on. 12.3V on the battery, 14.5V with the engine idling. Surely that suggests the alternator is ok??

Possibly not – I’ve had two cars in the past with knackered alternators, but it only happened after the car had been running for a while on the motorway. I remember a similar issue to yours – all the gauges, radio, wipers stopped working and the engine cut out as soon as I slowed down.

If your alternator is failing to charge your battery it would explain the low voltage.

I had a full electrical failure on my Renault Trafic a few years ago. Went from perfectly happy to no engine, lights, power steering, hydraulic brakes, nothing at all instantly. While driving down a steep road in the Alps, in a snowstorm, at night. That was “alarming”.

Turned out the battery connection had rattled loose, causing it to arc, which had eventually melted the connection!

Sounds like exactly what happened in my old Mondeo. Was the alternator.

Bit odd sailing along the M62 and all of the sudden, the dash lights die, everything zeroes but the car keeps running!

A low battery won’t cause the car to fail whilst driving, if the alternator is ok.

The alternator will generate enough power to run the car, you can remove the battery from a running car and it won’t stop.

Possibly not – I’ve had two cars in the past with knackered alternators, but it only happened after the car had been running for a while

When my alternator went, I started having starting problems, alternator was pushing out 14.3v when cold but after a run it tailed off to less than 13v. Possibly a diode or something but ended up just getting an uprated engineer.

Mols – on a diesel maybe – not on a petrol it won’t.
The diesel depends on what cutout it has – some are push to close so will keep going until the solenoid shuts it down.
Many modern ones use NC so removing the power shuts the solenoid valve instantly killing the engine.
IIRC – the VW’s will run once started if the alternator is good but remove the power and its done.

Mols – on a diesel maybe – not on a petrol it won’t.

No? Why?

When my alternator went, I started having starting problems, alternator was pushing out 14.3v when cold but after a run it tailed off to less than 13v. Possibly a diode or something but ended up just getting an uprated engineer.

Sounds familiar. I got an exchange alternator for not too many £££ so I didn’t bother trying to repair it.

I would check the Earth cables first then get the Alternator tested.
The main purpose of the battery is to start the vehicle and power anything whilst the engine is off.
Its the Alternator that powers everything whilst the engine is running and tops up the battery.
Modern cars have smart batteries now that stops the alternator from wasting energy trying to top up a charged battery.

” you can remove the battery from a running car and it won’t stop. “

in 1989 this was true….

today it is not.

” you can remove the battery from a running car and it won’t stop. “

But you risk knackering the alternator unless its got built in protection. It needs the load placed on it by the battery to avoid it going pop.

Sounds like a power supply relay issue. Soldered contacts inside go open circuit when hot, once cooled down after a few minutes circuit is made again and engine is able to start again. POSSIBLY relay no 109 in the relay/fuse box.