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P38A P1592 rough road signal implausible
- Thread starter kermit_rr
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You really need an oscilloscope to check the sensors properly. It's a shame the ECU stops talking to Nanocom if all sensors are working above 5mph. Makes finding an intermittent one quite difficult.
tomcat59alan
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Wheel bearing?
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Couldn't feel any movement, but maybe the movement in the ball joints was masking it.
Just been out to check the actual connection under the battery box and it seemed clean. Will try and do some measuring tomorrow.
Wish i had an oscilloscope!! Was tempted to but an eBay special a while back but don't know the first thing about them.. didn't want to end up with something designed for something else
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Silly Q. ...probably (I excel at these).
If the "Rough Road" OPTION/SETTING is selectable and able to be turned ON/OFF by Nanocom then... (bear with me here).....
Is the "Rough Road signal Implausible" message because its been turned on but there are no detectable conditions requiring it? i.e. Only on a very rough road do the ABS reluctor rings and sensors give a truly wide variance across wheels axles, so its ON and "implausible" given what the ABS ECU is seeing.
If the "Rough Road" OPTION/SETTING is selectable and able to be turned ON/OFF by Nanocom then... (bear with me here).....
Is the "Rough Road signal Implausible" message because its been turned on but there are no detectable conditions requiring it? i.e. Only on a very rough road do the ABS reluctor rings and sensors give a truly wide variance across wheels axles, so its ON and "implausible" given what the ABS ECU is seeing.
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I wondered about this too, but as there is no method to 'write' or otherwise make the setting permanent, it should be lost when you cycle the ignition ( i tried turning it off anyways, no effect)
also wondered if theres a programmatic mistake in nanocom, with on/off and active/inactive the wrong way round.
what bothers me is the fluctuating 'rough road volts' when thew engine is not running and the car is not moving.
be good to know from someone else with wabco D and a nano, what they see, ie. what is normal
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Strangely enough........ I have a Wabco-D on my bus. I could check what that page says when mine is just sitting idle and not moving.I wondered about this too, but as there is no method to 'write' or otherwise make the setting permanent, it should be lost when you cycle the ignition ( i tried turning it off anyways, no effect)
also wondered if theres a programmatic mistake in nanocom, with on/off and active/inactive the wrong way round.
what bothers me is the fluctuating 'rough road volts' when thew engine is not running and the car is not moving.
be good to know from someone else with wabco D and a nano, what they see, ie. what is normal
I also have a spare Wabco-D ECU, because.... they are like rocking horse-manure and not getting any cheaper
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Is that a hint? LolStrangely enough........ I have a spare Wabco-D ECU, because.... they are like rocking horse-manure and not getting any cheaper
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No, just an observation. I can take some readings for you from mine (which is working fine). My "spare" is staying as "my spare", I was just saying its good to have a spare because they are getting hard to find.
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Yep what i meant was, maybe i should be canny like you, before the manure gets shoveled up
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Yes. I spotted the trend that suggested they were getting hard to find at a decent price (a "NEW" one is just silly-money) so I bought one when I saw it on e-bay.
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They are hall-effect so as each tooth passes uou get a pulse which shows on an oscilloscope as a square wave. However, wire is wire. Stick an old style bulb with a piece of wire to attach it +V and the other end through the wire and to ground and it should light ip inless there is a break. Connector sounds like a good place to stick a wire in.
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Not had chance to do much yet but wheel bearing seems good and I've tested the sensor to the best of my ability and that seems good too.
Upper and lower ball joints show movement, but can't see that impacting on the sensor gap
Upper and lower ball joints show movement, but can't see that impacting on the sensor gap
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Just been digging a little. It seems the Rough Road output is a signal to the Motronic ECU, but not sure what that does when rough road is signalled. The Nanocom option probably just turns this signal on. Motronic ECU in Nanocom has this signal as Input value in "General 2", second page.
Bosch Motronic ECU Document says:
Rough road signal
This signal is also produced by the SLABS ECU. It is derived from the variations between each signal received from the four wheel speed sensors (see section on ABS for full description). The ECM alters its misfire detection strategy whenever a rough road signal is received. The ECM will not store details of a misfire fault at this time (see misfire detection strategy).
As far as the cause is concerned:
The key statement below is "The digital rough road signal is generated from the difference in rotational speed of each wheel." so if this error is triggering when stationary then it can only be sensor faults or ECU fault ?
Bosch Motronic ECU Document says:
Rough road signal
This signal is also produced by the SLABS ECU. It is derived from the variations between each signal received from the four wheel speed sensors (see section on ABS for full description). The ECM alters its misfire detection strategy whenever a rough road signal is received. The ECM will not store details of a misfire fault at this time (see misfire detection strategy).
As far as the cause is concerned:
The key statement below is "The digital rough road signal is generated from the difference in rotational speed of each wheel." so if this error is triggering when stationary then it can only be sensor faults or ECU fault ?
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BTW, if you want an oscilloscope at reasonable price get one of these Hantek 1008C USB Scope.
Enough channels to check all four sensors at same time, either stationary or during a drive . . . . . assuming you have a helper so you don't get nicked.
Enough channels to check all four sensors at same time, either stationary or during a drive . . . . . assuming you have a helper so you don't get nicked.
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I wrongly assumed when the TC and ABS lamps were lit, they didn't function. Wrong!
On a carpark, on full steering lock, no foot on the brake and doing 2mph at most, the system has a complete fit crashing and banging away and stops me dead in my tracks
On a carpark, on full steering lock, no foot on the brake and doing 2mph at most, the system has a complete fit crashing and banging away and stops me dead in my tracks
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More tests..
With everything plugged in, ignition on, engine not running;
Rough road volts 12/0v alternating
With wabco completely unplugged;
Rough road volts 12v steady
Given this is input to the motronic ecu, I'm wondering if nanocom is wrong. How can it receive a 12v signal if the end of the wire isn't plugged in?
With everything plugged in, ignition on, engine not running;
Rough road volts 12/0v alternating
With wabco completely unplugged;
Rough road volts 12v steady
Given this is input to the motronic ecu, I'm wondering if nanocom is wrong. How can it receive a 12v signal if the end of the wire isn't plugged in?
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If wabco is unplugged nanocom must be getting it from engine ecu.
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Yes, rough road volts is an engine ecu input, just not sure how it's getting it if abs ecu is unplugged
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Just tried the obvious and checked the connection
The motronic is supplying the 12v, not the wabco which must be switching.
I tried with the small plug disconnected, which is all 4 speed sensors and nothing else. Motronic still sees off road volts drop to zero, so i think my conclusion is the wabco must be faulty?
The motronic is supplying the 12v, not the wabco which must be switching.
I tried with the small plug disconnected, which is all 4 speed sensors and nothing else. Motronic still sees off road volts drop to zero, so i think my conclusion is the wabco must be faulty?
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