2.5Tdi XJ won’t start IOD fault?
 

Hi y’all

Thank you for a really informative forum.

I’m from South Africa. Hope you guys can help getting my XJ 2.5Tdi 2001 running again.
History: Engine was completely overhauled 20000km ago.
Ran well for a year. Started giving me a hard start and intermittent uneven idle that became permanent with a limp mode drive, like the turbo kicks in then dies.
Checked turbo pipes at acceleration while stationary, and the pipes have boost.

Found out number 1 injector was stuffed. Replaced, vehicle started , but same limp mode problem.
Starting got harder, until it refuses to start now.
Tested glow plugs, they’re fine.
Replaced glow plug relay.
Checked and bled the diesel pump and diesel pump to injector lines.
Performed several ECU resets by disconnecting the positive, shorting out for 30s, reconnect, key on, headlights on and off, key off.
Still wouldn’t start.
Suspected the diesel pump itself or the vacuum module.
Also noticed a sparking at battery terminals whenever I would reconnect, or boost from my car.
Randomly one morning after having the battery disconnected overnight, it started.
Next mornings no start.
Battery would drain quickly as well.
Started disconnecting various engine compartment connectors and pulling out fuses to locate the short. Sparking stopped when I removed IOD fuse. IOD fuse was not blown.
Thought it might be the SKIM module, but the key light comes on and then goes off after a say 30s, so I’m guessing it’s reading the key. It’s a grey key with a remote lock/unlock piece. The lock unlock stopped working at this point. It worked fine until I started with fuse pull outs.
Left battery disconnected, and the next morning, reconnected battery , it started and did so 4 times the next few hours,
The next day it wouldn’t start, and I picked up sparking on the battery reconnect even with the IOD fuse out.

Disconnected cables on all four doors for lock unlock and window control.
The roof light in the trunk was burned at the switch. Removed that and left the connector unconnected. The connector itself was bit burned out.
I disconnected the radio and other floor lights too.

I tested to MAP sensor and it seems fine.
At one point, if I had the key on, and disconnected the MAP, the diesel pump solenoid would rapidly click on and off. It never did that before. That’s stopped now.
I’ve pulled out all the fuses I could at the engine compartment fuse box(PCM?), and still have the short.

Any ideas where I can look next please?
Are there fuses /relays in the vehicle footwell box that could affect?
How can I test the diesel pump solenoid and the vacuum module and the SKIM module?
Could washing out the engine bay have gotten water where it shouldn’t be? But surely that would have dried out by now.
Also, what is the little sensor under the battery holder for?

Really hope you guys can help.
It’s frustrating, but it’s also been a huge learning curve that I appreciate .. lol

Thanks guys

Does the starter motor spins and turns the engine over ?
If it doesn't than check the clutch switch for now .
If it turns the engine over and does not start have a look at the crank shaft sensor located on top of bell housing if loose or wiring and connections going in to it.
There should be some power drain that would be normal depending on how much (I think around 200 miliamps or less ).
Also check all ground -12v connections for corrosion on engine block and chassie .
See how you go...

the sensor under the battery is a temperature sensor for the battery so that you dont overheat it. Reduces charge rate when battery is hot.

Amlav, Layback40 .. thank you
Engine cranks over, so I’ll look at the crank sensor
Will update progress here

Thanks guys