P38A Sorry! Abs/tc- update.

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Flossie

Flossie

Well-Known Member
Posts
11,001
Location
Shropshire
Got abs and tc lights on, 2001 dhse wabco D.
Plugged in the nanocom and I'm getting , on the sensor voltage readings.
Front left 2.33
Front right 2.25
Rear left 2.31
Rear right o.oo .
Now..
When I unplug each sensor and probe with my dmm I'm getting 5 v so now I'm confused, I've cleared the fault but lights don't go out and the fault returns after I do the quick trip to, ordinarily, knock the lights out.
The right hand rear sensor (showing zero volts) I decided to replace as the resistance reading was a little lower than the other 3, this has made no difference at all.
I did this yesterday, today I've now got Front left short to another on nanocom and the same 0 volts on Rear right still, but 5 v at the plug still.
Both Front sensors were new cheapies from island 4x4 around 6 months old rears are original wabco.
I'll source another Front sensor as my dmm says it's open circuit anyhow.
Resistance readings are
Front left open circuit
Front right 1017 ohms
Rear left 960
Rear right ( the brand new one) 1100.
Bit stuck now, and don't know what the zero volts on the rear right means when I have 5v at the plug.
All sensors are home, no damaged cables that I can see.
Brakes work well too.
 
That sounds similar the the problem i had.
I had a duff sensor, the resistance was slightly out and simply didn't work. It was about 3 days old, new one fixed it
 
kermit_rr said:
That sounds similar the the problem i had.
I had a duff sensor, the resistance was slightly out and simply didn't work. It was about 3 days old, new one fixed it
Click to expand...
But the nanocom no voltage thing is confusing me on rear right.
My mates is all working correct so I'll visit him over the weekend and see what his reads on the nano.
 
Flossie said:
But the nanocom no voltage thing is confusing me on rear right.
My mates is all working correct so I'll visit him over the weekend and see what his reads on the nano.
Click to expand...
I've had one show the desired resistance when tested but show no voltage on nanocom that was a week old ,put another new one in and sorted not come back on since
 
Bern768 said:
I've had one show the desired resistance when tested but show no voltage on nanocom that was a week old ,put another new one in and sorted not come back on since
Click to expand...
No voltage on the Nanocom may possibly refer to the return voltage from the sensor and so would indicate a duff sensor.
A DVM will read voltage even when there is a high resistance partial open circuit.
 
Datatek said:
No voltage on the Nanocom may possibly refer to the return voltage from the sensor and so would indicate a duff sensor.
A DVM will read voltage even when there is a high resistance partial open circuit.
Click to expand...
I did sort of wonder that if I'm understanding what you mean.
Power comes from somewhere(ecu maybe?) To each sensor (that's where I'm getting 5v) through the sensor and back to the ecu and the ecu sees and the nanocom reads a lower voltage at the ecu?
So I may have a dodgy 'return' connection or wire to the ecu.
Could be talking complete ball cocks though!
 
Flossie said:
I did sort of wonder that if I'm understanding what you mean.
Power comes from somewhere(ecu maybe?) To each sensor (that's where I'm getting 5v) through the sensor and back to the ecu and the ecu sees and the nanocom reads a lower voltage at the ecu?
So I may have a dodgy 'return' connection or wire to the ecu.
Could be talking complete ball cocks though!
Click to expand...
You are pretty much correct except that the sensor induces a wave form on the return line when the wheel is turning, with the wheel stationary there should be a static voltage on the return line, so yes a dodgy return line is a possibility. Power comes from the ECU.
 
Might be worth checking continuity from each sensor plug to the ECU as well. With the car stationary, I would expect similar voltage on both sides of the sensor. The wheel turning probably only puts a few 10's of mV waveform on the wires, superimposed on the 5V DC, but that will depend on speed & sensor gap.

upload_2022-5-27_17-43-37.png
 
Fixed:).
Incase anyone does a search.
Abs and tc lights on.
Nanocom showed no voltage right hand rear.
Sensor plugs at the axles showed 5v on all 4 plugs.
Resistance readings all good but right hand rear was a little lower.
Replaced right rear sensor.
No difference at all even though resistance was good.
Next day, plugged Nanocom in again and still no voltage at right rear but now front left showing short to another:rolleyes:.
Cheap front abs sensor off ebay fitted today and it's fixed:D.
Weirdly, the right rear sensor is now showing voltage on the nano o_O.
Fecked if I know:confused:.
I'm going to fit the old rear right sensor cos it might be a good spare if it doesn't show a fault.
 
'Parently...nano has the sensor positions wrong? RR is FL and so on. That would explain alot.
I'll go on bbs website after and see what I can find.
 
What a farce!:mad:
Just tried twice to sign up to the bbs site, get to the drop down for choosing which product I own and nanocom evolution isn't listed:mad:
Tried forgot password because I'm sure I signed up when I first got it but it just red rings my email address like its wrong or something. Same email address for donkies so it isn't that.
 
OK I'm in.
There's a post from 2017 asking if an update is available for this issue yet.
No response.
Version 35 or was it 135? I forget, is the latest update . Need to check my nano for that but its not looking promising tbh.
 
Flossie said:
OK I'm in.
There's a post from 2017 asking if an update is available for this issue yet.
No response.
Version 35 or was it 135? I forget, is the latest update . Need to check my nano for that but its not looking promising tbh.
Click to expand...
I did read some time ago that the problem was fixed, I know not if that is true, I don't have a Nanocom so I cannot check, I have a Faultmate.
 
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