Suzuki GSX-R 1000 Service Manual: DTC “c28” (p1655): secondary throttle valve actuator (stva) malfunction

Suzuki GSX-R 1000 Service Manual / Engine / Engine general information and diagnosis / Diagnostic information and procedures / DTC “c28” (p1655): secondary throttle valve actuator (stva) malfunction

Detected condition and possible cause

Detected condition

Possible cause

The operation voltage does not reach the stva.

Ecm does not receive communication signal from the stva. Stva can not operate properly or its motor locked

Stva malfunction.
Stva circuit open or short.
Stva motor malfunction.

Wiring diagram

Suzuki GSX-R. Wiring diagram

Troubleshooting

Caution

when using the multi-circuit tester, do not strongly touch the terminal of the ecm coupler with a needle pointed tester probe to prevent terminal damage.

Note

after repairing the trouble, clear the dtc using sds tool. Refer to “use of sds diagnosis reset procedures” .

Step

Action

Yes

Lift and support the fuel tank. Refer to “fuel tank removal and installation” in section 1g .
Remove the air cleaner box cover. Refer to “air cleaner element removal and installation” in section 1d .
Check the stva lead wire coupler (1) for loose or poor contacts.

Check whether the stvs open by turning the ignition switch on.

Is the operation ok?

Go to step 2.

Loose or poor contacts on the stva coupler.
Open or short circuit in the b/lg, p/w, g or w/b wire.
If wire and connection are ok, go to step 2.

Turn the ignition switch off.
Disconnect the stva lead wire coupler.
Check the continuity between each terminal and ground.

Special tool (a): 09900–25008 (multi circuit tester set)

Tester knob indication resistance (Ω)

Stva continuity ∞Ω¶ (infinity) (terminal . Ground)

If ok, then measure the stva resistance (between the p wire “a” and b wire “b”) and (between the w/b wire “c” and g wire “d”).

Special tool (a): 09900–25008 (multi
circuit tester set)

Stva resistance approx. 6.5 Ω (terminal “a” – terminal “b”, terminal “c” – terminal “d”)

B/lg, p/w, g and w/ b wire open or shorted to ground, or poor “3”, “4”, “27” and “28” connection.
If wire and connection are ok, intermittent trouble or faulty ecm.
Recheck each terminal and wire harness for open circuit and poor connection.
Replace the ecm with a known good one, and inspect it again. Refer to “ecm removal and installation” in section 1c .

Loose or poor contacts on the ecm coupler.
Replace the throttle body assembly with a new one. Refer to “throttle body disassembly and assembly” in section 1d .

Active control inspection

Set up the sds tool. (Refer to the sds operation manual for further details.)
Turn the ignition switch on.
Click “secondary throttle operating control” (1).

Suzuki GSX-R. Active control inspection

Click each button (2).
At this time, if an operation sound is heard from the stva, the function is normal.

Suzuki GSX-R. Active control inspection

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Other materials:

Exhaust system components
Exhaust pipe gasket Exhaust pipe assembly Ho2 sensor Connector : install the connector so that the chamfer side faces backward. Muffler chamber Muffler body Excv cable no. 1 Excv cable no. 2 When loosening or tightening the pulley bol ...

Ect sensor inspection
Refer to “dtc “c15” (p0115-h/l): ect sensor circuit malfunction” in section 1a . Inspect the ect sensor in the following procedures: remove the ect sensor. Refer to “ect sensor removal and installation” . Connect the ect sensor (1) to the circuit tester and place it in the o ...

Stp sensor removal and installation
Removal Remove the throttle body. Refer to “throttle body removal and installation” in section 1d (page 1d- 10). Remove the stp sensor (1) with the special tool. Special tool : 09930–11950 (torx wrench (5 mm)) Note prior to disassembly, mark the stp sensor’s origina ...