I'm getting P0501 and my HDC does not work 100% the way it should and theres little info on the forums about it so Id like to borrow a good scanner that can read abs related faults in the system. Tell me how much to rent it out for a couple days and we can work something out. Thanks

 

P0501 Vehicle speed sensor range/performance VSS implausible



Vehicle Speed Signal (VSS)
The VSS is used, by the ECM, to control idle speed and overrun cut off. The ECM receives the signal through a hard
wired connection direct from the SLABS ECU.
For vehicles fitted with an automatic gearbox, two vehicle speed signals are received by the ECM. The second signal
is derived from the main gearbox output shaft speed, and is sent to the ECM by the Electronic Automatic Transmission
(EAT) ECU though the Controller Area Network (CAN). The ECM compares the vehicle speed signal generated by
the SLABS ECU with that supplied via the CAN.
The ECM also receives transfer box information. This allows the ECM to take in to account the vehicle being driven
using low range gearing and compensate as necessary.
On vehicles with manual transmission, the SLABS signal is checked against a threshold value stored in ECM memory.
If other engine parameters indicate the engine is at high load and the VSS is below the threshold, a fault condition is
registered in the diagnostic memory.
The vehicle speed signal generated by the SLABS ECU is in the form of a pulse width modulated signal (PWM).
Pulses are generated at 8000 per mile, and the frequency of the signal changes in accordance with road speed. At
zero road speed the ECU outputs a reference signal at a frequency of 2Hz for diagnostic purposes.
Function
The input signal for the SLABS ECU is measured via pin 22 of connector C0637 of the ECM. The SLABS ECU
generates a PWM signal switching between 0 and 12 volts at a frequency of 8000 pulses per mile. For vehicles with
automatic gearbox the input signal for the EAT ECU is measured via pins 36 and 37 of connector C0637 of the ECM.
These pin numbers provide a bi-directional communications link using the CAN data bus.
In the case of a VSS failure on vehicles with automatic gearboxes, the ECM applies default values derived from the
EAT ECU. There are no default values for manual gearbox vehicles.
The VSS can fail in the following ways:
l Wiring short circuit to vehicle supply.
l Wiring short circuit to vehicle earth.
l Wiring open circuit.
In the event of a VSS failure, any of the following symptoms may be observed:
l MIL illuminated after 2 driving cycles (NAS only).
l Vehicle speed limiting disabled (manual transmission vehicles only).
l SLABS/HDC warning lamp on and audible warning.
Should a malfunction of the component occur the following fault codes may be evident and can be retrieved by
TestBook:
Rough road signal
When the vehicle travels across rough terrain, or on rough roads instability becomes evident in the drive train. The
ECM could interpret these vibrations as a 'false misfire'. To counteract this 'false misfire' the SLABS ECU generates
a rough road signal, sends it to the ECM so that the ECM can suspend misfire detection for as long as the vehicle is
travelling on the 'rough road'.

 

.....

 

xxdoylexx: I'm glad you figured out the problem with my truck, now please do tell us which part needs to be replaced?

Already been down that route and that still does not solve my problem nor pin point the issue. Especially seeing how the VSS setup is different on the D2 vs the D1. This has already been discussed in another thread. Other members are as stumped as i. I need to know why the HDC is not working properly and I need to find out if its linked with the transfer case and the pending code. So I figure a code scanner may be able to pick up a weak signal in some sensor or something like that, which will help me figure out whats wrong. So if anybody has a scanner that can read all Land Rover codes and faults and examine signals, please let me know how much to rent it for a couple days.

 

So it can be a number of things. Thus it a little bit of a bitch.. But hear are some hints.

Possible causes
- Faulty Vehicle Speed Sensor
- Vehicle speed sensor harness or connectors is open or shorted
- Vehicle speed sensor circuit poor electrical connection
- Faulty Engine Control Module (ECM)

When is the code detected?
The signal sent by the vehicle speed sensor to ECM is out of range.
Possible symptoms
- Engine Light ON (or Service Engine Soon Warning Light)
- Speedometer may not work properly
- Transmission shifting problem
P0501 Description
The vehicle speed sensor outputs a 4 pulse signal for every revolution of the rotor shaft, which is rotated by the transmission output shaft via the driven gear. After this signal is converted into a more precise rectangular waveform by the waveform shaping circuit inside the combination meter, it is then transmitted to the Engine Control Module (ECM). The ECM determines the vehicle speed based on the frequency of these pulse signals.




Read more: P0501 Vehicle Speed Sensor 'A' Range/Performance OBDII Engine Light Trouble Code | Engine-Codes.com

 

Not sure what it'd cost to rent one and pay for shipping two-ways... But you can buy the for $163.92 (w/ free 2-day shipping if you're a Prime member) and it will do everything a regular OBD can PLUS it reads and resets ABS and SRS faults. Seems like a heck of a deal, I've thought about picking one up but keep convincing myself I should probably just wait until I can spring for the Nanocom...

 

Or, if you have a tablet or Laptop, the CDP+ is a good deal for around $100 shipped.

 

in transition to new apartment which is more $$$$ so until i manage a second job money is real tight. I have every intention of buying an advanced scan tool that also reads live data but for now I just want to know if there are any transmission codes or if any sensors are getting less than normal signal strength. I may just say hell with it and bring the truck to DAP but id like to be able to give them some kind of idea where to start. Dont want to pay extra $$$ while they look blindly for a problem. Alsi need them to install my SS brake lines and flush system again so maybe that will work.

 

I wish I was closer, I'd be happy to do a free scan...

 

A heads up.... the Autel 619 does not read SRS codes. I bought one last month, updated the software only to discover it will not diagnose my SRS warning light.

I returned it and I am waiting for my Nanocom to arrive.