Battery / oil light

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Peugeot Boxer desiel 2.2tdi 07 plate - Did actually have this issue last year after a long trip abroad and it has happened again, where randomly on start up the engine management light comes on and battery sounds flat, turn the key off and on again and it will fire up. Today this happened and battery light comes on too. Just got to Bilbao port in way home after driving around Spain around 1,200 miles, then got to port, through customs and same issue. We r in boat but know this problem is unresolved. We have had a new starter fitted, 2 new batteries, new oil pressure sensor switch and a new alternator as this has been happening on and off for a couple of years hence all the new parts and bizarrely only usually happens after a long journey. This is a self built camper with a split charger and a solar panel system with very few electronics taking power. I will say this is one of the many who had a water ingress problem into engine bay and pretty much now come to the conclusion it’s the wiring harness??? Anyone had the same problem. Just to note oil and battery are always fine.
 
Be careful - low battery "conditions" can fry the airbag ECU.
Check the battery, a cheap multimeter will confirm if its flat or not, but as above, earth straps are common failures, and even ones that look good can have internal corrosion - so if not changed, changed in last 5y, change it. (You can always add an additional one elsewhere)
 
As a "reboot" appears to solve it, if it's not an earth strap issue could it be the ECU or similar?
 
It could still be the earth strap. A bad earth strap can cause low voltage and /or poor charging, which could cause ECU errors which are cleared by a reboot.
And an extra earth strap is easy and cheap. It'd be worth doing in any case. If it fixes the problems you're sorted. If it doesn't, you have improved the earthing.
 
It could still be the earth strap. A bad earth strap can cause low voltage and /or poor charging, which could cause ECU errors which are cleared by a reboot.
And an extra earth strap is easy and cheap. It'd be worth doing in any case. If it fixes the problems you're sorted. If it doesn't, you have improved the earthing.
Thanks for all the replies, it cleared on reboot on last leg of our journey and we r home now 👍 so want to take ur advice. Are you talking earth strap that is connected to the battery terminal or is there another earth strap under the bonnet?
 
Flat/low battery voltage , and bad earth causing the starter to turn slowly , will result in low voltage supply to sensors and may register in the ECU as a fault (out of range) code . Most of these will reset if voltage returns to normal resulting as an in range reading at sensor on next start sequence.
 
There are two earth cables: one goes from the battery negative to a point on the chassis, but that's normally an insulated cable, and doesn't suffer much twisting or corrosion. It's generally easy to see and check.

The other earth strap is sometimes an uninsulated woven metal strap connecting the engine to the chassis. It has to be flexible because the engine is mounted on shock-absorbing brackets and it has to be conductive because the engine mounts are usually rubber.

The problem is that movement of the engine can fray it away, and it can corrode in the salt spray environment under the engine. Generally, they're hard to see and damage can go unnoticed. Vehicle makers tend to skimp on the size of the cable to save a few pence, so if it is half frayed/corroded/broken you've little current carrying margin to rely on.

There is no harm in adding additional earth straps between the engine and the chassis and also between the chassis and the battery negative.
 
There are two earth cables: one goes from the battery negative to a point on the chassis, but that's normally an insulated cable, and doesn't suffer much twisting or corrosion. It's generally easy to see and check.

The other earth strap is sometimes an uninsulated woven metal strap connecting the engine to the chassis. It has to be flexible because the engine is mounted on shock-absorbing brackets and it has to be conductive because the engine mounts are usually rubber.

The problem is that movement of the engine can fray it away, and it can corrode in the salt spray environment under the engine. Generally, they're hard to see and damage can go unnoticed. Vehicle makers tend to skimp on the size of the cable to save a few pence, so if it is half frayed/corroded/broken you've little current carrying margin to rely on.

There is no harm in adding additional earth straps between the engine and the chassis and also between the chassis and the battery negative.
 
Hi thanks very much very helpful- would like to check the earth strap anyway but will probably do what you have suggested and just put another on. Where is the present one likely to be found as battery is of course sitting in a housing in the passenger footwell - do I need to get under the van?
 
The existing battery earth strap will be easy to find: just follow the wire from the battery terminal.
The earth strap from the engine may be more tricky to find. You probably will need to crawl underneath, but it varies from vehicle to vehicle. They're designed to be easily assembled by robots on an assembly line, not to be easy to maintain.
The good news is that you can fit an additional one more or less anywhere that's convenient. Just find a chunky bolt on the engine you can fit one end to, and somewhere suitable on the chassis that you can bolt the other end to.
Be sure to clean the connections down to bare metal, and to rust-proof it afterwards, with paint or with grease.
 
IF you're replacing the earth strap.... Try to avoid the cheap nasty Braided type...

Go for the proper thick insulated cable types...
They suffer much less from corrosion etc and IMHO give better and more reliable conductivity.
Agreed. If possible, it's worth getting the extra flexible ones with lots of finer wires in them, rather than the ones with fewer, fatter wires.
A more flexible cable is easier to install and transfers less engine noise.
 
Hi thanks very much very helpful- would like to check the earth strap anyway but will probably do what you have suggested and just put another on. Where is the present one likely to be found as battery is of course sitting in a housing in the passenger footwell - do I need to get under the van?
The earth strap usually associated with your van is the one between the engine and chassis it's behind the air filter attached to the gearbox r/h/s.
also worth a look just above that not easily seen below the ECU where the main loom comes across the engine and winds around its own mounting before rising to ECU it has been known to wear thru the insulation causing a lot of different problems, Happen to me
 
If it is a bad earth put a voltmeter between the -ve battery terminal and a bolt on the engine and measure the volts drop, that will definitively tell you if you have a bad earth.
 

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