It doesn't matter, it's the same ECU for a 4.6 and a 4.0. You can change the engine size from 4.6 to 4.0 with a Nano.

Is it dumping all the air or is it just the normal self levelling when you switch off and get out of the car?

Not so sure. I fitted a 98 engine, complete with engine loom, into a 97 car. As the 97 and 98 use different O2 sensors the plugs were different so we left them disconnected thinking it would detect they weren't there and run a default fuelling strategy. Car fired up and ran normally but when taking it for a run, it adjusted the mixture so it got progressively weaker and weaker until it would no long run. The GEMS sensors are 5-0V Titania which give 0V when rich, so, thinking it was running very rich, it just kept leaning the mixture off. Rather than modify the looms, I made up 8 short lengths of cable with male and female connectors to connect them and it ran perfectly after that.

However, this was on a UK car intended to have the sensors so an Aus spec ECU may respond differently. Or, as long as you've got a Nano to use the security learn feature, fit the ECU from one of the cars without the sensors so it won't expect to see them.

There's 3 different ones for the V8 and 2 for the diesel. V8 are 94-97, 98 and 99 onwards while diesel are 94-98 and 99 on. According to Island 4x4 they have:
V8 94-97 in stock at £599.99
V8 99 onwards in stock at £999.99
Diesel 94-98 in stock at £599.99
Diesel 99 onwards in stock at £194.99

So for anyone with a late diesel, best buy one now and put it on the shelf until it will be needed. But everyone else will need deep pockets unless you happen to be, like me, with a 98 V8, there's a problem. I've got an iffy one I replaced 3 or 4 years ago, when they were only just over £100, that I think will be being pulled apart and refurbished and kept for the just in case moment.

It would be worth finding out what the differences are but ideally that needs someone with multiple ones to compare. Underbonnet wiring loom is different between a 97 and a 98 so there must be differences.....

No way Nigel. Your tapping was definitely valve gear, a cam follower or rocker arm. If it was the head gasket it would have blown completely years ago.

Mine is set for 55mph so goes off at 52, ideal for the never ending 50mph average speed camera zones as I don't have cruise control.

It did cause me a panic a few years ago. On our first drive to Latvia, halfway through Poland, Dina took over the driving so I could get some sleep. Within 10 minutes of dozing off, I was abruptly woken by the dreaded beep, beep, beep but by the time I looked there was no warning on the dash for a message of impending doom, so told Dina to pull in at a layby. Knowing that the cause of the beeps would be displayed when the engine was switched off, she switched it off but there was no message. Restarted the engine, no warning lights or fault messages and everything seemed fine so set off again only for the beeps to start again. This time I saw the warning saying Speed Limit. As I had never used it, it was set for the default 20mph and she had accidentally switched it on when she had been trying to wash the screen.....

I suspect the access problems would be the same doing the LH head on a LHD vehicle. Other than the bolts holding the heat shields in place being rusted solid and the heads corroded so much you can't get a grip on them, the steering column gets in the way making it even more awkward.

It is the passenger side, you can see the dipstick. I would agree. We've no way of knowing why the gasket failed but either bolts not torqued evenly or one 'soft' stretch bolt is all that would be needed. So there is nothing to say the other one will suffer in the same way. The steering column does get in the way but I've found that taking the wheelarch liner out and going in from the side means you've got a lot easier access to the heatshield bolts, that pesky rear exhaust manifold bolt and the steering column can stay in place.

Courtesy of Garvin I picked up his known good spare SRD100501 ECU today and have just got in after trying it in the car. I can now say it isn't the ECU as it made no difference at all. That just leaves it losing the speed signal at speed on one or more wheels so I now have an excuse to treat myself to a scope so I can look at the output from each wheel at higher speeds than the Nano will display them. One halfshaft with the reluctor ring has been replaced already (LH rear), I'm still slightly suspicious of the RH front, I've had a look at the RH rear and that looked fine but no idea about the LH front. That may be in the same state as the other front one.

It did pass the MoT by the way as the tester used the decelerometer at 15mph and the brakes are fine at that speed, the problem only occurs at higher speeds.

I'd go for the cheaper pipe and slobber it in Hammerite paint (or just give the one you have a good wire brushing and slobber it in Hammerite). Where was the gasket blowing? Out the side or into the Vee? Into the Vee can usually be confirmed by the noise increasing if the oil filler cap is removed, out the side can often bee seen as flames coming out of the joint. However, this can only be seen from underneath and the joint will be concealed from view by the exhaust manifold, hence the original (wrong) diagnosis.

Yes. With the driver pack connected to the valve block, go to the connector that would connect to the outside world (C152). See the following diagram but bear in mind this is the loom side and not the plug side so it is mirror image.

Easy enough to follow as the two pins for ground (10 and 11) re black and the two for power (12 and 13) are red. Put power and ground onto those two pairs (a standard spade terminal will go over both pins) and then you can apply power to the pin for the each valve. If you hear the valve go click, it is working, if it doesn't, that channel is dead.

It a Wabco thing, the ECU stops communicating over 5mph.

Anyway, I've spent today on the car and thought I was going to declare Bolt the winner. But not.....

It needs an MoT and one thing I had noticed was that the RH front axle oil seal was leaking. Not a specific MoT fail I don't think, but I know the tester wouldn't be impressed so, ignoring the ABS for the time being, I set about changing that, It was pretty obvious that the hub had been out before and the dust shield around the ABS ring had been slotted rather than just having a hole so the ABS sensor doesn't need to be removed. Got the hub out and turning the hub it felt a bit like a worn bearing but didn't, if you know what I mean. I realised it was the ABS ring rubbing on something and then noticed this

a dent in the dust shield. Had a closer look at the ring and noticed some teeth had bits of rust on them

While others had almost merged into one with general crud

So, could it be that due to this the signal from the sensor was getting corrupted at higher speeds resulting in brakes that worked perfectly at low speed but the ABS was kicking in at higher speeds? Cleaned it all out and carried on with the job I had started. As I had suspicions about the brake light switch, I'd got a new, genuine one of those just to rule it out so fitted that too. Once all back together I took it for a test run.

ABS light goes out at 5 mph, no faults shown on the dash so apply the brakes at about 15mph, perfect. Go a bit faster and applying the brakes at 25mph, the ABS can be heard and felt operating just as before. As another test, as the RH rear sensor was such a nice fit I could pull it out with my fingers, I managed to get my arm down behind the wheel and pulled the sensor out. As soon as I started moving the dash beeped and came up with ABS Fault and Traction Failure, as you would expect when it doesn't see normal rotation on all 4 wheels. Drove off down the road, tried the brakes at 25mph and the ABS kicked in just as before. But, with a detected ABS fault, the ABS would normally be turned off? Shoved the RH rear sensor back in, drove a little further to confirm that everything was now back to normal and the fault message was no longer there. Then opened the bonnet and pulled fuse 38 that feeds the ABS ECU. Started up and got an immediate ABS Fault on the dash, drove off and applied the brakes at 25mph, perfect at 40mph, perfect and at 50mph still perfect.

This now all seems to point towards the ECU applying the ABS when it doesn't, and shouldn't, need to. It shouldn't do anything when it has detected a fault (or at least the earlier Wabco C doesn't, my other half used the Ascot with one duff wheel sensor, a dash full of warning lights and brakes that worked perfectly for 3 months last year) but it is doing. However, when I called my local tame dismantler (Avenger 4x4), the response when I asked if he had SRD100500 or 501 on the shelf, his reply was simply, rocking horse manure.....

There's a couple on eBay at the moment but not cheap and although the owner wants it sorting and is quite happy to pay £200 for an ECU, I'm not one to just throw bits at a car and hope they fix it, I want to know it will fix it first. However, I should have the opportunity to borrow one next week so will know once and for all.

As for the MoT, it's booked in tomorrow morning. As the brake test will be done at low speed with the deccelerometer, I'm hoping the tester doesn't go fast enough to notice.....

Thanks, didn't realise you were on here too Lefty.

Up to £1126 at the moment so has gone beyond the original target of a grand. Still got just under two months to go before the jump date of 22 April so no idea what it will get up to by then.

Exactly what I saw on both the inlet and outlet valves. That would make sense when the brakes aren't applied but I would have expected them to change when the brake pedal is pressed. Nanocom document says:

• Inlet valve: This shows the voltage being applied to this valve by the ABS ECU. When driven the
voltage should be around 2.8 to 3.6 Volts and when not being driven should be around 0 to 0.5 Volts.
• Outlet valve: This shows the voltage being applied to this valve by the ABS ECU. When driven the
voltage should be around 2.8 to 3.6 Volts and when not being driven should be around 0 to 0.5 Volts.

and I'm assuming the valves will be driven when the brakes are applied......

Thanks Leo, I'll check that but as both are switching I suspect that isn't the problem. Can you check the inlet and outlet voltages when the brakes are applied for me please? I would have thought the voltage should change when the brakes are applied but they aren't doing.

Latest update is that I suggested to the owner that he pulled Fuse 38 and tried it. Despite having the ABS and TC lights on permanently, the brakes are working perfectly....

No afraid I don't, all I've got is a graphical multimeter which would be able to show one sensor but with a lot of messing around swapping from one to another. Not only that, if the sensors were reporting differing speeds, I would expect it to bring up an ABS fault on the dash and log a fault too.

A scope is one of those things that I wish I had once or twice a year but I was spoilt when working with having £40k+ worth of high quality test equipment as personal issue so the affordable stuff always seems inferior to what I got used to using.

The car is coming back to me on Monday so it might be too late. However, the readings I want to know is whether the two brake light switches should both be the same (both open and then both closed when the brake pedal is pressed) or if they should swap over so one open and one closed as on my GEMS. There are also screens showing Inlet and outlet valve voltages. These are all at 0.00V (with the occasional 0.06V showing intermittently) but do not change when the brake pedal is pressed. I would have expected them to but they don't.

It's a bit of a pain that the ECU disconnects diagnostics once over about 5mph, being able to see what it is doing at speed would be very useful.

I haven't but I did think after the owner had taken it away I could have pulled the ABS fuse so it doesn't do anything. At least he'll have brakes, just no ABS or TC (and a dash full of warning lights).

I'm still a little confused by some of the readings I get on the Nanocom though. Both my cars have the earlier Wabco C system and this is Wabco D. When looking at the two brake light switch status, on the C system one is open and one is closed and they swap over when the brake pedal is pressed. On the D system they both show the same status and change from open to closed (or the other way round) when the brake pedal is pressed. That would suggest that the switches are different but the parts list shows the original part number for a C system car supersedes to the same one as fitted to a D system car which makes me think they must be interchangeable? The inlet and outlet valve voltages not changing when the brake pedal is pressed doesn't seem right either but I need to find a D system equipped car with working brakes to stick the Nano on and see what that reads.