DIY PGMFI Diagnostics - Code 17 VSS

[ECU-MAN]

Disclaimer: The following is provided as a GUIDE ONLY, and neither myself nor Ozhonda take any responsibility for the outcomes of someone else doing the following. You follow these steps at your own risk!


No part of this DIY is to be reproduced with out acknowledgment of the site and author it came from, ie me and ozhonda.com. Do not rip parts off and claim them as your own.




VSS Sensor "Vehicle Speed Sensor". The VSS sensor is commonly located on the rear of the gearbox. On OBDO cars that have a speedo cable have the VSS in the cluster and is driven by the speedo cable. The VSS on/off type of sensor pulsing 5v on and off 4 times per revolution. The ECU monitors the VSS to determine vehicle speed. VSS is also used by the PCM and cruise control.




Aim:

Diagnose code 17.







Required:

Basic Testing

- Digital Multi Meter
- paper clip



Symptoms

A faulty VSS sensor will trigger code 17. VSS failure is common and the speedo and odometer drop out suddenly, if you have and automatic the D4 light will more than likely come on as well.







Basic Test


- Perform a Visual inspection and make sure the VSS sensor is Connected,



VSS Sensor Pin out Picture

OBDO

check VSS at ECU connector


OBDI




wire side of connector





**** Voltage Test ****


Set your multimeter to DC Volts ( 20v scale )




Step 1


Check the VSS sensor for its reference Voltage from the ECU, Connect the Black Lead from your multimeter to the chassis for a good ground. Back probe* the VSS pin 2 with the Red lead while the sensor is connected.



KOEO* you should get 12v

If you get 12v proceed to step 2,

if you do not get 12v, repair open or short circuit to that supplies 12v to the VSS





STEP 2



Check VSS sensor for a good ground. Leave your Red lead from the above test on Pin 2 of the VSS. Back probe your Black lead into Pin 1 of the VSS.

KOEO* you must get 12v

If you get 12v proceed to step 3,


if you do not get 12v, repair open or short circuit to ECU from Pin 1 of VSS to the bellow ECU Pin ( also see continuity test below )



OBDO = A16
OBDI = A26
OBDIIa = A9
OBDIIb = B20



Leave your Black lead of the multimeter as is and move the Red Lead from Pin 1 of the TPS to the positive battery terminal. You should get 12v. If not, repair the wire between Pin 1 of the VSS and Pin listed above to the ECU





STEP 3




Check the VSS Signal. Connect the Black Lead from your multimeter to the chassis for a good ground. Back probe* the VSS with the Red lead to Pin 3 of the VSS sensor while the sensor is connected.


KOEO* you should get 5v

as the front wheels rotate the 5v should alternate between 0v to 5v. ( note; rotate both wheels at the same time. not just one )


If you do not get a signal on Pin 3, replace the VSS sensor with a known good one and retest. If you do get a signal at Pin 3, then check the signal at the ECU end.



OBDO = B16
OBDI = B10
OBDIIa = C18
OBDIIb = C23




If you get a good signal at Pin 3 of the VSS and no signal on the above ECU Pin, repair the Open circuit between the above ECU Pin and Pin 3 of the VSS.





***** Its is always best to check sensor inputs at the ECU side *****





**** Continuity Test ****




Set your multimeter to continuity. This setting is mostly a picture if a sound .))) when you touch the Red and Black leads together on your meter it should beep.





STEP 1

make sure the Ignition is off and unplug VSS Connector and the ECU Connectors for this test


Continuity test between VSS Pin 1 and ECU, Connect your Red multimeter lead on the TPS Pin 1, Back probe* the Black multimeter lead on the ECU Pin bellow that suits your car.




OBDO = A16
OBDI = A26
OBDIIa = A9
OBDIIb = B20



your multimeter should beep and read short or 000.0ohms.







STEP 2


make sure the Ignition is off and unplug VSS Connector and the ECU Connectors for this test



Continuity test between VSS Pin 3 and ECU, Connect your Red multimeter lead on the VSS Pin 3, Back probe* the Black multimeter lead on the ECU Pin bellow that suits your car.




OBDO = B16
OBDI = B10
OBDIIa = C18
OBDIIb = C23




your multimeter should beep and read short or 000.0ohms. Place the black multimeter lead on a good ground source. You should not get beeping, this is testing for short to ground.


If any of your continuity tests fail between the VSS and ECU, repair the OPEN in the wire between the VSS and ECU that failed.

If any of your continuity tests fail between the TPS and ground, Find the short circuit and repair it. look for squashed wires, or for damage to any part of the PGMFI loom.




**** Frequency Test ****


Set your multimeter to Hz scale





Step 1




Check the VSS sensor for its output frequency to the ECU, Connect the Black Lead from your multimeter to the chassis for a good ground. Back probe* the VSS Pin 3 with the Red lead while the sensor is connected.


to make the VSS produce a signal, you have to rotate the wheels with speed. Safest way is to have someone drive the car while you look at the meter to record the results

with the vehicle travelling at 60km/h you should get about 0.040khz

as vehicle speed increases frequency increases



You can also test the VSS signal at the ECU connectors



OBDO = B16
OBDI = B10
OBDIIa = C18
OBDIIb = C23



If you do not get a signal, replace the VSS.



* Notes

KOEO = Key On Engine Off

KOER = Key On Engine Running

Back probe the sensor, use a paperclip and push it into the connector then touch/clip your multimeter lead to the paper clip


Disclaimer: The following is provided as a GUIDE ONLY, and neither myself nor Ozhonda take any responsibility for the outcomes of someone else doing the following. You follow these steps at your own risk!