Suzuki GSX-R 1000 Service Manual: DTC “c23” (p1651-h/l): to sensor circuit malfunction

Detected condition

Possible cause

0.2 V ≤ Sensor voltage < 4.8 V

• To sensor circuit open or short.
•  To sensor malfunction.
•  Ecm malfunction.
• To sensor circuit is open or ground circuit open
• To sensor circuit is open or shorted to ground or vcc circuit open.

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.

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

Step

Action

Yes

No

1

1. Turn the ignition switch off.
2.  Remove the front seat. Refer to “exterior parts removal and installation” in section 9d .
3.  Remove the ap sensor from the bracket.
4.  Check the to sensor coupler (1) for loose or poor contacts.

   If ok, then measure the to sensor resistance.

5. Remove the to sensor.
6.  Measure the resistance between terminal “a” and terminal “c”.

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

Tester knob indication resistance (Ω)

To sensor resistance 16.5 – 22.3 KΩ (terminal “a” – terminal “c”)

Is the resistance ok?

Step

Action

Yes

No

1

1. Turn the ignition switch off.
2.  Remove the front seat. Refer to “exterior parts removal and installation” in section 9d .
3.  Check the to sensor coupler (1) for loose or poor contacts.

   If ok, then check the to sensor lead wire continuity.

4. Disconnect the to sensor coupler.
5.  Check the continuity between the r wire and b wire. If the sound is not heard from the tester, the circuit condition is ok.

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

Tester knob indication continuity test ( )

6. Disconnect the ecm coupler. Refer to “ecm removal and installation” in section 1c .
7.  Insert the needle pointed probes to the lead wire coupler
8. Check the continuity between the b wire and terminal “31”. Also, check the continuity between b/br wire and terminal “35”.

Special tool
(a): 09900–25008 (multi
circuit tester set)
(b): 09900–25009
(needle-point probe set)

Tester knob indication continuity test ( )

Ecm coupler (harness side)

Is the continuity ok?

Step

Action

Yes

No

1

1. Turn the ignition switch off.
2. Remove the front seat. Refer to “exterior parts removal and installation” in section 9d .
3.  Check the to sensor coupler (1) for loose or poor contacts.

   If ok, then check the to sensor lead wire continuity.

4. Disconnect the to sensor coupler.
5.  Check the continuity between the b wire and ground.

   Also, check the continuity between the b wire and b/br wire. If the sound is not heard from the tester, the circuit condition is ok.

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

Tester knob indication continuity test (

)

6. Disconnect the ecm coupler. Refer to “ecm removal and installation” in section 1c .
7.  Insert the needle pointed probes to the lead wire coupler.
8. Check the continuity between the r wire and terminal “7”. Also, then check the continuity between b wire and terminal “31”.

Special tool
(a): 09900–25008 (multi
circuit tester set)
(b): 09900–25009
(needle-point probe set)

Tester knob indication continuity test (

)

Ecm coupler (harness side)

Is the continuity ok?

2

1. Connect the ecm coupler and to sensor coupler.
2.  Insert the needle pointed probes to the lead wire coupler.
3.  Turn the ignition switch on.
4.  Measure the voltage at the wire side coupler between b wire and b/br wire.

Special tool
(a): 09900–25008 (multi
circuit tester set)
(b): 09900–25009
(needle-point probe set)

Tester knob indication voltage ( )

To sensor voltage (normal) 0.4 – 1.4 V ((+) terminal: b – (–) terminal: b/br)

5. Dismount the to sensor from its bracket and measure the voltage when it is leaned 65° and more, left and right, from the horizontal level.

Special tool
(a): 09900–25008 (multi
circuit tester set)
(b): 09900–25009
(needle-point probe set)

To sensor voltage (leaning) 3.7 – 4.4 V ((+) terminal: b – (–) terminal: b/br)

Is the voltage ok?

• R, b or b/br wire open or shorted to ground, or poor “7”, “31” or “35” 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 .

• Loosen or poor contacts on the ecm coupler.
•  Open or short circuit.
•  Replace the to sensor with a new one. Refer to “to sensor removal and installation” in section 1c .

refer to “no spark or poor spark” in section 1h  for details.