940 blowing fuse 1 and not starting

[Laird Scooby]

Originally Posted by coolpurks

Thank you I’ll have a look - will it start with it removed? If this cures it is it best to buy a new one?

Thank you!

It will start with it unplugged, yes. However it won't run well once warmed up as it will go into Limp Mode and substitute a default value for the Lambda sensor which will cause rich running. Ultimately that could poison your cat so shouldn't be driven for any length of time.

The Bosch engine management system is hyper sensitive to some non-Bosch components, the Lambda sensor is one of them so if that is the fault, renewal won't be cheap.

Let's find the fault before getting to that stage though.

[coolpurks]

I unplugged the lambda sensor, from the red plug at the top of the engine bay near the firewall, and then turned ignition to position to but didn’t crank the engine, and it blew the fuse immediately.

So is it likely there could be a short somewhere else now then? Thanks

[Laird Scooby]

Originally Posted by coolpurks

I unplugged the lambda sensor, from the red plug at the top of the engine bay near the firewall, and then turned ignition to position to but didn’t crank the engine, and it blew the fuse immediately.

So is it likely there could be a short somewhere else now then? Thanks

No, it's not likely there's a short somewhere else, it's an absolute certainty!

You need to make the short-tester as i doubt you have a limitless supply of fuses. It will also help protect your wiring from a dead short, restricting the current to 5A~ so less likely to cause further damage while you test and trace.

[mocambique-amazone]

Originally Posted by coolpurks

I unplugged the lambda sensor, from the red plug at the top of the engine bay near the firewall, and then turned ignition to position to but didn’t crank the engine, and it blew the fuse immediately.

So is it likely there could be a short somewhere else now then? Thanks

You did disconnect this?
https://www.ebay.co.uk/itm/Oxygen-O2...wAAOSwb55eUZm3

[mocambique-amazone]

remove Fuse 11, fuel pump. fuse 1 in.
try to start again
Won't start for shure, if the fuse will stay the intank pump is gone

[mocambique-amazone]

fuse 1:
Fuse 11, fuel pump
fuel injection system
ignition system
heated oxygen sensor
RSR (radio suppresion relay)
immobilizer (never had a problem aka "blown fuse" with this

good luck

[mocambique-amazone]

https://ww2-secure.justanswer.com/up...28_02_0000.jpg

different model (940 I till 1995)
wrong side of steering wheel

still the same place, ok nearby......

[coolpurks]

Originally Posted by mocambique-amazone

You did disconnect this?
https://www.ebay.co.uk/itm/Oxygen-O2...wAAOSwb55eUZm3

Yes I disconnected that.

I will now try fuse 11.

I will make the bulb tester too. Thank you

[360beast]

The best advice I can give you is just do what Ash and Dave say as they know their stuff, follow the procedure they lay out and you will be fine. I've never known a forum with such intelligent people before, I'm a mechanic but I never really dealt with electrics before so if I have a problem with my 940 electrics then the first thing I do is email Dave.

[coolpurks]

Ok so I have found a bulb holder for one of the rear lights with a bulb in it will this work for the tester? I’ll solder a couple of wires on.

Just thinking back, the only wiring that could have possibly been disturbed, was any wiring near to and including the open bonnet sensor, and the wiring to the fan relay, and any other wiring that appears to go towards the back of the headlights near the fan/radiator. I moved this out the way to remove the intercooler. I clipped it all back in place after I re-fitted the intercooler – do you have any idea whether any of these wires could be linked to fuse one? No worries if not!