Suzuki GSX-R 1000 Service Manual: DTC “c29” (p1654-h/l): secondary throttle
position sensor (stps) circuit malfunction
Detected condition and possible cause
Detected condition |
Possible cause |
C29 |
Output voltage is not within the following
range.
Difference between actual throttle opening
and opening calculated by ecm is larger
than specified value.
0.15 V ≤ Sensor voltage < 4.85 V |
- Stp sensor maladjusted.
- Stp sensor circuit open or short.
- Stp sensor malfunction.
- Ecm malfunction.
- Stp sensor circuit shorted to vcc or ground circuit
open.
- Stp sensor circuit open or shorted to ground or vcc
circuit open.
|
P1654 |
H |
Sensor voltage is higher than specified
value. |
L |
Sensor voltage is lower than specified
value. |
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” . |
C29 (use of mode select switch)
Step |
Action |
Yes |
No |
1 |
- Turn the ignition switch off.
- Lift and support the fuel tank. Refer to “fuel tank removal and
installation” in section 1g .
- Check the stp sensor couplers (1) and (2) for loose or
poor contacts.
If ok, then measure the stp sensor input voltage.

- Disconnect the stp sensor coupler (1).
- Turn the ignition switch on.
- Measure the input voltage between the r wire and
ground. Also, measure the voltage between the r wire
and b/br wire.
Special tool
(a): 09900–25008 (multi
circuit tester set)
Tester knob indication
voltage ( )
Stp sensor input voltage
4.5 – 5.5 V
((+) terminal: r – (–) terminal: ground, (+) terminal: r
– (–) terminal: b/br)

Is the voltage ok? |
Go to step 3. |
- Loose or poor
contacts on the ecm
coupler.
- Open or short circuit
in the r wire or b/br
wire.
|
P1654-h (use of sds)
Step |
Action |
Yes |
No |
1 |
- Turn the ignition switch off.
- Lift and support the fuel tank. Refer to “fuel tank removal and
installation” in section 1g .
- Check the stp sensor couplers (1) and (2) for loose or
poor contacts.
If ok, then check the stp sensor lead wire continuity.

- Disconnect the stp sensor couplers (1) and (2).
- Check the continuity between the y/w wire and r 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 ( )

- Disconnect the ecm couplers. Refer to “ecm removal and
installation” in section 1c .
- Check the continuity between the y/w wire and terminal
“18”. Also, check the continuity between the 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 couplers (harness side)

Is the continuity ok? |
Go to step 3. |
Y/w wire shorted to
vcc, or b/br wire open. |
P1654-l (use of sds)
Step |
Action |
Yes |
No |
1 |
- Turn the ignition switch off.
- Lift and support the fuel tank. Refer to “fuel tank removal and
installation” in section 1g .
- Check the stp sensor couplers (1) and (2) for loose or
poor contacts.
If ok, then check the stp sensor lead wire continuity.

- Disconnect the stp sensor couplers (1) and (2).
- Check the continuity between the y/w wire and ground.
Also, check the continuity between the y/w 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 ( )

- Disconnect the ecm couplers. Refer to “ecm removal and
installation” in section 1c .
- Check the continuity between the y/w wire and terminal
“18”. Also, check the continuity between the r wire and
terminal “7”.
Special tool
(a): 09900–25008 (multi
circuit tester set)
(b): 09900–25009
(needle-point probe set)
Tester knob indication
continuity test ( )
Ecm couplers (harness side)

Is the continuity ok? |
Go to step 2. |
R or y/w wire open, or
y/w wire shorted to
ground. |
2 |
- Connect the ecm couplers.
- Turn the ignition switch on.
- Measure the input voltage between the r wire and
ground. Also, measure the input voltage between the r
wire and b/br wire.
Special tool
(a): 09900–25008 (multi
circuit tester set)
Tester knob indication
voltage ( )
Stp sensor input voltage
4.5 – 5.5 V
((+) terminal: r – (–) terminal: ground, (+) terminal: r
– (–) terminal: b/br)

Is the voltage ok? |
Go to step 3. |
Open or short circuit in
the r or b/br wire. |
3 |
- Turn the ignition switch off.
- Connect the ecm couplers and stp sensor couplers.
- Remove the air cleaner box cover. Refer to “air cleaner element
removal and installation” in section 1d .
- Disconnect the stva lead wire coupler (1).

- Insert the needle point probes to the lead wire coupler.
- Turn the ignition switch on.
- Measure the stp sensor output voltage at the coupler
(between the y/w wire (+) and b/br wire (–)) by turning
the secondary throttle valve (close and open) with your
finger.
Special tool
(a): 09900–25008 (multi
circuit tester set)
(b): 09900–25009
(needle-point probe set)
Tester knob indication
voltage ( )
Stp sensor output voltage
secondary throttle valve is closed: approx. 0.7 V
secondary throttle valve is opened: approx. 4.1 V
((+) terminal: y/w – (–) terminal: b/br)


Is the voltage ok? |
- R, y/w or b/br wire
open or shorted to
ground, or poor “7”,
“18” 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 .
|
If check result is not satisfactory, replace the stp sensor with a
new one. Refer to “stp sensor removal and installation” in section 1c . |
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 ...
Detected condition and possible cause
Detected condition
Possible cause
No gear position switch voltage
Gp switch voltage is not within the following range.
Gp switch ...
Other materials:
Exhaust emission control system
description
The exhaust emission control system is composed of the pair system, exhaust
control system, ho2 sensor, threeway
catalyst system and isc system. The fresh air is drawn into the exhaust ports
through the pair control solenoid
valve and pair reed valves. The pair control solenoid valve is operat ...
Clutch cable play inspection and adjustment
Inspect clutch cable play
every 6 000 km (4 000 miles, 12 months)
Inspect and adjust the clutch cable play “a” as follows.
Clutch cable play “a”
10 – 15 mm (0.4 – 0.6 In)
Lift and support the fuel tank. Refer to “fuel tank
removal and installation” in section 1g (page 1g-
9).
  ...
Fail-safe function table
Fi system is provided with fail-safe function to allow the engine to start
and the motorcycle to run in a minimum
performance necessary even under malfunction condition.
The engine can start and can run even if the signal in the table is not
received from each sensor. But, the engine
...