Throttle Valve Opening Signal Circuit Check

Reference:

Throttle valve opening signal is pulse.

Oscilloscope waveform of throttle valve operating signal as shown in the figure.

Connect oscilloscope between terminals "E61-4" and "C51-3-6" of connected ECM connector (for H27 engine model) or between terminals "E61-6" and "C51-3-26" of connected ECM (PCM) connector (for H25 engine model).

Fig 1: Identifying Throttle Valve Opening Signal

Courtesy of SUZUKI OF AMERICA CORP.

Step	Action	Yes	No
1	DTC check  Check DTC referring to "DTC CHECK " or "DTC CHECK ". Is there a DTC related to throttle position sensor?	Go to applicable DTC flow.	Go to Step 2.
2	Throttle valve opening signal circuit check  Turn ignition switch ON. Check voltage between terminal "E61 -4" (for H27 engine model [A] of ECM) or "E61-6" (for H25 engine model [B] of PCM) connector connected and ground. Does voltage vary linearly according to throttle opening?	Throttle valve opening signal circuit is OK.	Go to Step 3.
3	Supply voltage check  Disconnect connector from ECM (for H27 engine model) or PCM (for H25 engine model) with ignition switch OFF. Check for proper connection to ECM at terminal "E61-4" (for H27 engine model [A]) or to PCM at terminal "E61-6" (for H25 engine model [B]). If OK, connect "BLU" wire terminal of main relay to ground with service wire. Turn ignition switch ON. Check voltage between terminal "E61 -4" (for H27 engine model [A]) or "E61-6" (for H25 engine model [B]) of PCM connector and ground. Is it 10-14 V?	Check TP sensor and circuits referring to "DTC P0121: THROTTLE POSITION (TP) SENSOR CIRCUIT PERFORMANCE PROBLEM " or "DTC P0121: THROTTLE POSITION SENSOR CIRCUIT PERFORMANCE ". If OK, substitute a known-good ECM (for H27 engine model) or PCM (for H25 engine model) and recheck.	Check "GRY" wire for open and short. If OK, proceed to cruise control module power and ground circuits check.