PWM Fault Code.

I thought an update might be in order. Despite being able to change my original SLAB's VIN No. and back again. I have re tried the replacement SLAB and it will not change. I thought perhaps I could change the engine ECU VIN but there doesn't seem to be anyway to do that. However the replacement SLAB does solve a number of issues. For example the original SLAB only sends voltage to one wheel where as the replacement sends volts to all wheels. This proves the original SLAB has an internal fault I think. I'll try option B on the ABS and see if that fixes the three amigoes. But the PWM communications error has returned and I do not know what problems that causes. Also I cannot clear faults on the replacement due to communications problem. So I'll continue to play. Luckily I have a few vehicles, so can cope without the L/R at this point, but I need it to tow my trailer with a car on at Easter all in all a 5000 kilometre trip. Anyone with any thoughts don't hold back.

IMO you should try with another SLABS ECU too

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Originally Posted by sierrafery

IMO you should try with another SLABS ECU too

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Yes I agree. Been looking on Ebay but the ones advertised are all recalled versions. Reconditioned $700 AU and new over $1000. Unfortunately the whole car isn't worth that sort of expebditure on top of the other work I've done. I'll look for a later version second hand one. Actually you can almost buy a complete spares car for $1200 or so. I need back bumper bar, love electric seats etc. So may be I need to look at that as an option. More on my ABS module strip down tomorrow.

I removed the ABS module, and though dreading having to do so, found it pretty straight forward, apart from the brake fluid that the rags I had prepared didn't soak up. So I sprayed it all with metho. My engine bay is pretty good no oily bits at all so I want to keep it looking good. Stripped the ABS down and found that much of the insulation was missing from the shuttle switch wires. Possible earth fault. Then I measure 3000 ohms and 2000 ohms when switches are operated but not 1000 ohms. I would have thought 1000 and 2000 made the 3000 but apparently not on my Landrover. Just no 1000 ohms at all. Checked the continuity of the shuttle valve pins in the module block witha buzzer and pressure on one pin causes the buzzer to go on and off. Another fault. So even with a new shuttle switch I will need to do option B. Then inside the module there was a lot of muck. Looks like it might have once been brake grease or vasaline. So another potential fault.

Question should the solenoid valve rods be greased???

There is little protection from water ingress into this area because there is no gasket between the two parts, even if the bolts are extremely tight to undo. Bit odd. One solenoid rod looked water marked. Top left rod first photo.

Attachment 168229Attachment 168228

Carried out option B. Refitted the ABS without greasing the solenoid rods. Lost one of the 4 amigos. Now have just 3, the ABS light has gone. I have decided that both SLABS are faulty and they have different problems. I have bought another SLAB. Awaiting delivery.Cannot bleed the brakes with either Nanocom or the Foxwell. So now waiting for an assistant to show up at the workshop door so I can conduct a manual bleed. I started to make a detailed list of what should be seen on every terminal of the slabs connector when the vehicle is both stopped and moving. But yet to test them.

Carried out a manual bleed. Despite continually going around all the wheels there is still a small amount of air some where in the system. Haven't been on the road yet as I left the Nanocom plugged in and on over 24 hours and the battery is too flat to start the car. I have a spare battery might jump start it as I don't feel like waiting for the charger to do its thing. I found a note that I wrote back at the begining of this fiasco and it says the compressor will not work automatically unless the PWM communications is working. Wonder where I read it, Rave, or perhaps a forum? The compressor is dependant on doors, etc, and speed because speed above a certain KPH stops the compressor working. I must follow up more while I wait for the replacement SLAB.

Finally all is well. PWM code depended on changing the VIN in the SLAB to the same as the engine ECU. There was three faults altogether. Both SLABS were faulty. So I got another and it worked without changing the VIN but suspect the cruise control would not have. The shuttle valve switchs did not show 1000 ohms. So replaced them. The pin in the ABS module that connects to the shuttle valve switches was also intermittently faulty so by passed it with Option B. So all is well. I now know a lot more about the vehicle. The computers are not so frightening if you have a known good replacement, after testing to prove that they are indeed faulty. Thanks for the input guys.

Congrats on getting it sorted - but I can't quite tell if you were actually able to change the VIN to the correct VIN on the replacement SLABS ECU? And if so, did this work with Foxwell (530?)?

That's what I need to do.

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Originally Posted by Nashvegas

Congrats on getting it sorted - but I can't quite tell if you were actually able to change the VIN to the correct VIN on the replacement SLABS ECU? And if so, did this work with Foxwell (530?)?

That's what I need to do.

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Sorry about the delay in reply. Yes changed the VIN with the Foxwell on the second replacement SLAB. Wouldn't change it on the first replacement. All works great now.