Secondary Throttle position sensor

Agree with @Gert. The secondary throttle is fully controlled by the ECU, and the STPS feeds secondary throttle position back directly into the ECU. This means that only the ECU can tell you it's faulty, and if you replace it, you need a special interface (dealers only) to calibrate it. If there's no strong indication that it's broken, leave well alone.

The primary throttle is a different kettle though. That one is controlled by your right wrist and the only way the ECU can know what the position of that right wrist is, is the primary throttle position sensor. The one Suzuki uses is a simple variable resistor with a ribbon resistor in it, and a wiper arm against it. This will eventually start giving false readings due to debris and wear. Some people have revitalised their TPS by blowing compressed air or contact cleaner into it. But a TPS is relatively cheap and I consider it a wear item, to be replaced after 50.000 km or so.

Replacement of the primary TPS requires removal of the plastics, tank and airbox. Not hard, just time consuming. You also need a special "security" Torx bit. T25s, from memory. And after replacement you need to calibrate it. This requires you put the bike into dealer mode, and then rotate the TPS in very tiny increments until the reading on the dash is right, and the bar changes at a certain RPM. Fiddly but important. Plenty of write-ups on this forum.

If you know exactly what to look for, you can do the TPS calibration with the airbox and tank, and even all of the plastics on the bike. But you need to nudge a few hoses out of the way, and reach in in a special way to get this done. Impossible to explain if you haven't done a TPS replacement (with plastics, tank and airbox removed) before.

If the ECU indeed lights up the FI, and throws an STPS-related Cxx code, then yes, you're on the right track. Never heard anything like this on this forum though.

The secondary throttle valves are really easy to inspect, if you think that's where the rattling comes from. If you take off the airbox, they're the first set of butterfly valves that are visible. At rest they're usually around half open. If you switch the ignition on, they're supposed to sweep back and forth by way of self test, and then they should remain almost fully open. And the plates should move in unison.

The STPS sensor is on the side of the throttle body housing, attached to the butterfly axle. Note that on the VStrom almost all of the sensors are only on the front cylinder, and there's an adjustable mechanical linkage to the rear. The ECU assumes that the conditions at the rear are identical to the front, so it can inject the same amount of fuel. That's why adjusting the linkage is so important. However, you only have the instrumentation (a vacuum gauge) to adjust the primary throttle valve linkage properly - this is also known as a TBS or Throttle Body Sync. Adjusting the mechanical linkage for the Secondaries requires dealer-specific equipment. That's why we usually advice to leave this well alone.

If you suspect that the rough running of your bike is related to the secondaries, you can also remove the secondaries temporarily or permanently. The butterflies are attached to the axle with two tiny screws. Use a magnetic screwdriver or something to prevent them from falling in the cylinders! The engine will usually run perfectly fine without the secondaries, as they're only used to close the throttle when the ECU detects that you are exceeding the safety boundaries of the bike (in low gear: so much torque that you can induce a wheelie, in high gear: an RPM that would lead to an overspeed of the bike.) If you don't drive like a hooligan you should not need the secondaries at all. And supposedly the secondaries also close just a bit to induce turbulence in the throttle body airflow, to help with the atomisation of the fuel. Never witnessed this first-hand though, don't know the details.

Rob Edwards said:

# sorry forgot to put year on#
It a 2010 (L0)

Looking for where this sensor is located, Part Number, And how hard it will be to complete the job


Thanks

Click to expand...

Hi All thanks for the info however I went and got the bike plugged in today and there scanner showed the fault as a the throttle body motor not the secondary position sensor.😖

my issue is now that
1. I cant seem to purchase the throttle motor separately.
2. I have purchased a complete throttle body from a DL650 2021 AM1 as the sensors are the same as the ones on the 2010 (According to my mechanic)

can anyone confirm before I start to pull the bike apart that yes the sensors are the same and that the secondary throttle motor will fit

if the parts dont ft what are my options

Thanks