ABS light and speedo stopped
23-01-2014, 09:53 PM
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ABS light and speedo stopped
Hi,
The ABS warning light has come on and the speedo has stopped working ( plus management light)
I have read the diagnostic codes and get P0500 and P0121.
From what I have googled, I am guessing it is likely to be a speed sensor but would this be on one of the wheels, or on the gearbox? Would I have both?
Also I have looked up the P0121 code and it refers to "Throttle Position Sensor Switch". I have absolutely no idea what this might be. Can anyone shed any light?
Many thanks, Graham
The ABS warning light has come on and the speedo has stopped working ( plus management light)
I have read the diagnostic codes and get P0500 and P0121.
From what I have googled, I am guessing it is likely to be a speed sensor but would this be on one of the wheels, or on the gearbox? Would I have both?
Also I have looked up the P0121 code and it refers to "Throttle Position Sensor Switch". I have absolutely no idea what this might be. Can anyone shed any light?
Many thanks, Graham
23-01-2014, 09:58 PM
#2
PassionFord Post Whore!!
You need to establish if your car has a VSS (the speed sensor in the gearbox) or if get's it's road speed info from the ABS.
I assume the latter if you have ABS warning on too. Are you able to scan the ABS?
Throttle position sensor is the sensor on the throttle body, usually a 3 wire job.
Make sure the cable hasn't been adjusted so the throttle isn't closing fully.
I assume the latter if you have ABS warning on too. Are you able to scan the ABS?
Throttle position sensor is the sensor on the throttle body, usually a 3 wire job.
Make sure the cable hasn't been adjusted so the throttle isn't closing fully.
P0121
Error Description
Throttle Position (TP) Circuit Performance Problem The TP sensor circuit is monitored by the PCM for a non closed throttle position at idle.
If key ON engine running self-test terminates upon placing the transmission range selector in gear (DRIVE or REVERSE) or when closing the throttle (idle) after opening it (in PARK or NEUTRAL) the TP closed throttle position is not attained, the test fails. Binding throttle linkage Damaged throttle body TP circuit open to PCM Damaged TP sensor SIG RTN circuit open to TP sensor Drive vehicle, bring to a stop, turn key OFF. Start vehicle, run key ON engine running self-test at idle.
Access KOER diagnostic trouble codes on scan tool.
Error Description
Throttle Position (TP) Circuit Performance Problem The TP sensor circuit is monitored by the PCM for a non closed throttle position at idle.
If key ON engine running self-test terminates upon placing the transmission range selector in gear (DRIVE or REVERSE) or when closing the throttle (idle) after opening it (in PARK or NEUTRAL) the TP closed throttle position is not attained, the test fails. Binding throttle linkage Damaged throttle body TP circuit open to PCM Damaged TP sensor SIG RTN circuit open to TP sensor Drive vehicle, bring to a stop, turn key OFF. Start vehicle, run key ON engine running self-test at idle.
Access KOER diagnostic trouble codes on scan tool.
P0500
Error Description
Vehicle Speed Sensor (VSS) Malfunction Indicates the powertrain control module (PCM) detected an error in the vehicle speed information. Vehicle speed data is received from either the vehicle speed sensor (VSS), transfer case speed sensor (TCSS), anti-lock brake system (ABS) control module, generic electronic module (GEM), or central timer module (CTM).
If the engine rpm is above the torque converter stall speed (automatic transmission) and engine load is high, it can be inferred that the vehicle must be moving. If there is insufficient vehicle speed data input, a malfunction is indicated and a DTC is set. On most vehicle applications the malfunction indicator lamp (MIL) will be triggered when this DTC is set. Open in VSS+/VSS- harness circuit.
Open in TCSS signal or TCSS signal return harness circuit. Short to GND in VSS harness circuit. Short to GND in TCSS harness circuit. Short to PWR in VSS harness circuit. Short to PWR in TCSS harness circuit. Open or short in the vehicle speed circuit(s) (VSC) between the PCM and appropriate control module.
Damaged VSS or TCSS. Damaged wheel speed sensors. Damaged wheel speed sensor harness circuits.
Damage in module(s) connected to VSC/VSS circuit. Damage drive mechanism for VSS or TCSS. Monitor VSS PID while driving vehicle. This DTC is set when the PCM detects a sudden loss of vehicle speed signal over a period of time.
If vehicle speed data is lost, check the source of where the vehicle speed input originates from: VSS, TCSS, ABS, GEM or CTM. Note: On some MSOF applications, VSS and TCSS PID can be monitor. However if no TCSS PID is available and VSS PID is zero, TCSS circuitry frequency must be checked for loss of sensor signal.
If another vehicle electronic module has generated the P0500 and the vehicle does not receive its vehicle speed input from one of the above mention sources (VSS, TCSS, ABS, GEM or CTM).
Check the PCM for Output Shaft Speed Sensor (OSS) DTCs.
On OSS applications the PCM uses the OSS to calculated the vehicle speed. If no OSS DTCs are found check for correct PCM configuration.
Check PCM configuration for correct tire size and axle ratio.
Error Description
Vehicle Speed Sensor (VSS) Malfunction Indicates the powertrain control module (PCM) detected an error in the vehicle speed information. Vehicle speed data is received from either the vehicle speed sensor (VSS), transfer case speed sensor (TCSS), anti-lock brake system (ABS) control module, generic electronic module (GEM), or central timer module (CTM).
If the engine rpm is above the torque converter stall speed (automatic transmission) and engine load is high, it can be inferred that the vehicle must be moving. If there is insufficient vehicle speed data input, a malfunction is indicated and a DTC is set. On most vehicle applications the malfunction indicator lamp (MIL) will be triggered when this DTC is set. Open in VSS+/VSS- harness circuit.
Open in TCSS signal or TCSS signal return harness circuit. Short to GND in VSS harness circuit. Short to GND in TCSS harness circuit. Short to PWR in VSS harness circuit. Short to PWR in TCSS harness circuit. Open or short in the vehicle speed circuit(s) (VSC) between the PCM and appropriate control module.
Damaged VSS or TCSS. Damaged wheel speed sensors. Damaged wheel speed sensor harness circuits.
Damage in module(s) connected to VSC/VSS circuit. Damage drive mechanism for VSS or TCSS. Monitor VSS PID while driving vehicle. This DTC is set when the PCM detects a sudden loss of vehicle speed signal over a period of time.
If vehicle speed data is lost, check the source of where the vehicle speed input originates from: VSS, TCSS, ABS, GEM or CTM. Note: On some MSOF applications, VSS and TCSS PID can be monitor. However if no TCSS PID is available and VSS PID is zero, TCSS circuitry frequency must be checked for loss of sensor signal.
If another vehicle electronic module has generated the P0500 and the vehicle does not receive its vehicle speed input from one of the above mention sources (VSS, TCSS, ABS, GEM or CTM).
Check the PCM for Output Shaft Speed Sensor (OSS) DTCs.
On OSS applications the PCM uses the OSS to calculated the vehicle speed. If no OSS DTCs are found check for correct PCM configuration.
Check PCM configuration for correct tire size and axle ratio.
Last edited by GVK.; 23-01-2014 at 10:03 PM.
23-01-2014, 10:13 PM
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Thanks for the help.
Yes I assume it's the latter as the ABS light is on too. But have no idea how to scan the ABS. Is this something I can do with my code reader?
Is there any trick to find out which sensor is faulty? I assume I just need to take each one off in turn and measure the resistance through it?
I was assuming/ hoping the throttle sensor reading was also based on same problem, but one thing at a time I guess. Once (or if) I get the ABS and speedo sorted, I can move on to throttle would seem like a plan!
Thanks
Graham
Yes I assume it's the latter as the ABS light is on too. But have no idea how to scan the ABS. Is this something I can do with my code reader?
Is there any trick to find out which sensor is faulty? I assume I just need to take each one off in turn and measure the resistance through it?
I was assuming/ hoping the throttle sensor reading was also based on same problem, but one thing at a time I guess. Once (or if) I get the ABS and speedo sorted, I can move on to throttle would seem like a plan!
Thanks
Graham
23-01-2014, 10:21 PM
#4
PassionFord Post Whore!!
Most DIY code readers aren't able to scan ABS etc, only the engine ECU
(PCM in Ford speak)
Ideally need the ABS codes reading, and if the wheel speeds sensors showing to be working in the ABS live data and go from there. Without looking into it I wouldn't expect a fault on one ABS sensor to lose the speedo altogether, I could be wrong.
It may be an instrument cluster fault, or ABS module fault, or wiring between the two even.
(PCM in Ford speak)
Ideally need the ABS codes reading, and if the wheel speeds sensors showing to be working in the ABS live data and go from there. Without looking into it I wouldn't expect a fault on one ABS sensor to lose the speedo altogether, I could be wrong.
It may be an instrument cluster fault, or ABS module fault, or wiring between the two even.
30-01-2014, 05:27 PM
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Hi
Reporting back. I have been able to use a more advanced scanner and had a reading that says
C1236 Speed Wheel LR input signal Missing
C1155 Speed Wheel sensor LF Input circuit failure
Do you think it is likely that simultaneously I have a fault with both front and rear sensors? Is it possible there is a problem where the left side plugs in to main unit?
If the latter, where will I find the main ABS unit please? Sorry to be so thick!
It is a basic 2005 1.3.
Many thanks, Graham
Reporting back. I have been able to use a more advanced scanner and had a reading that says
C1236 Speed Wheel LR input signal Missing
C1155 Speed Wheel sensor LF Input circuit failure
Do you think it is likely that simultaneously I have a fault with both front and rear sensors? Is it possible there is a problem where the left side plugs in to main unit?
If the latter, where will I find the main ABS unit please? Sorry to be so thick!
It is a basic 2005 1.3.
Many thanks, Graham
22-07-2014, 02:58 PM
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ABS Light and speedo stopped working
Has there been any resolve to this problem on here. I also have code P0121 which relates to throttle. I'm not convinced this is a co-incidence. This car has been sitting on a drive for about 4 weeks. Hasn't gone anywhere but I had to charge the battery before I could drive it for the first time 3 days ago. I can't take it anywhere however as I've no speedo. There is no symptoms of anything being wrong. I should also start this as a new thread seeing as yours was a few months back. 
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24-07-2014, 03:55 PM
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Thank you for this information - My neighbour took it up the road a bit so I'll find out if this was the case, thank you Dojj. Will also ask if he's had a look at the wiring.
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