Discovery 2 TD5 auto not starting

when you plugged the hawkeye in didnt you check for fault codes in the engine ECU too? , that fault code you found is stored in the ATC ECU and it wont affect the start-up : P0705 (14, 23) =* Gear position switch,incorrect outputs = Maintains current gear in low range, limp home mode in high range. Shift pressure to maximum, harsh gear shifts/engagement.

... also, did you clear the code and it came back?

sierrafery said:

when you plugged the hawkeye in didnt you check for fault codes in the engine ECU too? , that fault code you found is stored in the ATC ECU and it wont affect the start-up : P0705 (14, 23) =* Gear position switch,incorrect outputs = Maintains current gear in low range, limp home mode in high range. Shift pressure to maximum, harsh gear shifts/engagement.

... also, did you clear the code and it came back?

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Yes checked engine ecu for codes and nothing. Tried clearing the p0705 error but it doesn't clear.

Been fighting the urge to set fire to the disco and took another look at this problem today.

I got the wife to try and crank the disco whilst I tested the starter, i get no power on the small wire.

So ran a cable from the small connection up to the top of the engine. I then touched it to the + on the battery. The disco starts and runs for about 2 secs.

Fuel pump runs as it always has done, so don't think that's an issue. I put a new starter relay in so that is ruled out.

I'm thinking this is related to the alarm system not working. The engine is starting but other critical electrical systems aren't active so it shuts down. Does this sound possible? Maybe a bcu failure?

the alarm/immobiliser cuts the fuel pump too...that's why i didnt suspect it from the beginning.... it's possible that the BCU lost syncronisation with the ECM and it triggers the passive immobilisation... if u have tester u can disable the passive immobilisation for test,... u can also check for water ingress at the BCU's plugs cos it's quite common

Took the bcu out and checked the board. All looked ok but cleaned it up and put it back in. The alarm now works, which was sort of good but painful on the ears!!

But still not starting. The keyfob doesn't work. I had purchased a new fob a while ago but hadnt got round to programming it, so got that and programmed it with hawkeye. But the bcu doesn't appear to save the code, everything appears to work but after programming I go back into hawkeye and it tells me the fob needs programming.

Used hawkeye to disable the passive immobilisation. But that hasn't changed anything.

If I got a 2nd hand bcu do I just plug it in? Or does it need programming? Or has anybody got any other suggestions?

Or does anybody want to swap a defender 300tdi for a broken disco td5???? Which I wanted in the first place but got over ruled by the wife

the BCU needs syncronisation with imobiliser, instrument pack and IDM(for that one put ignition on pos I and leave it so 3 minutes)... doable with hawkeye(for the imobiliser you have to approach it via EMS - programing)... and if it has a greater mileage stored in it than the one in the odometer the greater will be assumed and displayed

richsmith78 said:

Yes checked engine ecu for codes and nothing. Tried clearing the p0705 error but it doesn't clear.

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The engine will only start if in park or neutral (start inhibit). If the xyz is duff then the ecu cannot verify it is in park or neatral and hence start inhibit and it will not crank and start.

sabredylan said:

The engine will only start if in park or neutral (start inhibit). If the xyz is duff then the ecu cannot verify it is in park or neatral and hence start inhibit and it will not crank and start.

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The xyz switch was replaced. I checked the wiring loom and it appears to be ok and not rubbed anywhere. But can someone tell me what colour wire signals to the bcu that the transmission is in park?

I don't think it's a simple as that. According to RAVE, switch W outputs 12v when in park (but it also does in D, as well as Y and Z). So there's more to it than just the Park switch.

richsmith78 said:

The xyz switch was replaced. I checked the wiring loom and it appears to be ok and not rubbed anywhere. But can someone tell me what colour wire signals to the bcu that the transmission is in park?

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The wire is green with yellow stripe and runs from the the xyz switch to a connector behind the window switches and handbrake, from here it changes to green with red stripe and goes to slabs ecu under the dash on passenger side.

If its blowing fuse 25, I'd crawl under the car and check the gearbox harness from the xyz plug to the rubber grommet, where the harness enters the car. These harness's are known for chaffing on top of gearbox/transfer box and shorting. Its secured on top of gearbox by a clip with 17mm nut. Remove this to better examine it. Give it a good move about and away from gearbox and try starting it.

Failing that check the connector plugs on the slabs ecu for water ingress. Its prone in this area, as water can get past the scuttle seal.

Hope this helps.

Going back to the first post in this thread, how are you getting 14.4 from a battery in a vehicle that hasn't run for weeks and won't start now?

Hello please tell me that you found the problem with the vehicle because i have the exact problem and dont know what to do next.