chazuk Posted July 3, 2013 Share Posted July 3, 2013 (edited) I've always found the pas on the supra to light over a ton its like a feather I have no real feel what is going on , is there any way of adjusting it? Edited July 3, 2013 by chazuk (see edit history) Quote Link to comment Share on other sites More sharing options...
Iky Posted July 3, 2013 Share Posted July 3, 2013 I've always found the pas on the supra to light over a ton its like a feather I have no real feel what is going on , is there any way of adjusting it? This is usually due to a dodgy speedo convertor, PAS ecu thinks it's going slower than what it is. I've read it usually involves cutting a pink wire behind the speedo. Quote Link to comment Share on other sites More sharing options...
stevie_b Posted July 3, 2013 Share Posted July 3, 2013 (edited) Cheap speed converters can cause the power steering to be over-assisted at moderate speeds (50mph ish). That doesn't match your symptoms exactly, but worth considering. To elaborate: the cheap ones simply scale back the speed signal by 5/8 to get mph from kph. That works fine for the speedo dial itself, but not great for the ECU and other peripherals that also use the speed signal. The ECU is programmed to provide more steering assistance at, say, 30mph than it does at say 50mph. But at 50mph, if the speed signal is simply scaled back, the ECU thinks the car is only doing 30mph, and provides more assistance than it would if it knew the car was going at 50mph. Edited July 3, 2013 by stevie_b (see edit history) Quote Link to comment Share on other sites More sharing options...
chazuk Posted July 3, 2013 Author Share Posted July 3, 2013 Cheers I will look into this I know my speedo convertor is on the gearbox , anyone know how I can test diagnose for sure ? Quote Link to comment Share on other sites More sharing options...
stevie_b Posted July 3, 2013 Share Posted July 3, 2013 (edited) Look at the converter. If it's only got one output, then you'll have the problem I described. The better converters send a scaled-back signal to the speedo dial, and an unaltered signal to the ECU. None of this will make a difference if over-assistance kicks in at about a ton though. By the time you get to 100 leptons, the ECU provides minimal (or no) steering assistance, and it doesn't make a difference if you scale it back by 5/8 or not. Edited July 3, 2013 by stevie_b (see edit history) Quote Link to comment Share on other sites More sharing options...
chazuk Posted July 3, 2013 Author Share Posted July 3, 2013 Look at the converter. If it's only got one output, then you'll have the problem I described. The better converters send a scaled-back signal to the speedo dial, and an unaltered signal to the ECU. None of this will make a difference if over-assistance kicks in at about a ton though. By the time you get to 100 leptons, the ECU provides minimal (or no) steering assistance, and it doesn't make a difference if you scale it back by 5/8 or not. Okay cheers I think it was a 5wire one but maybe 1 or 2 wires did not get used I will have to check now, interesting it feels just as light at 60 as it does at 140 and I am running 255's on the front and it feels like I could be steering a push bicycle wheel its really off putting, do you know where I would find pas electric valve located ? Quote Link to comment Share on other sites More sharing options...
stevie_b Posted July 3, 2013 Share Posted July 3, 2013 I might be wrong, but I think the PAS control box sits just above where the head unit is. I can't remember if the PAS box gets its signal from the ECU, or directly from the speed sensor (i.e. before the signal reaches the ECU). I would first check the error codes logged by the ECU. If it's logged error code 42, that means the ECU isn't getting a speed signal at all, and if this is the case, whatever the speed converter is trying to do, the ECU will simply provide maximum assistance regardless of the car's speed. Quote Link to comment Share on other sites More sharing options...
Iky Posted July 3, 2013 Share Posted July 3, 2013 Could also be the solenoid plunger gummed up. I removed mine on my 60K miles supra and it was all gummed up. The filter clogged with debris. Quote Link to comment Share on other sites More sharing options...
chazuk Posted July 3, 2013 Author Share Posted July 3, 2013 I might be wrong, but I think the PAS control box sits just above where the head unit is. I can't remember if the PAS box gets its signal from the ECU, or directly from the speed sensor (i.e. before the signal reaches the ECU). I would first check the error codes logged by the ECU. If it's logged error code 42, that means the ECU isn't getting a speed signal at all, and if this is the case, whatever the speed converter is trying to do, the ECU will simply provide maximum assistance regardless of the car's speed. Okay thanks I will check the ecu for fault codes. Could also be the solenoid plunger gummed up. I removed mine on my 60K miles supra and it was all gummed up. The filter clogged with debris. Where is the solenoid located ? Quote Link to comment Share on other sites More sharing options...
Iky Posted July 3, 2013 Share Posted July 3, 2013 Okay thanks I will check the ecu for fault codes. Where is the solenoid located ? On the actuall steering rack http://www.clublexus.com/forums/ls400/343856-all-in-one-power-steering-fix-s-solenoid-acv-plug-drain-flush-bleed-system-diy.html After I cleaned this, my steering felt real nice. Easy at low speeds and stiffens up nicely when cruising on the motorway. Quote Link to comment Share on other sites More sharing options...
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