LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Toyota >> 2004 >> Matrix Base, FWD, Automatic >> Repair and Diagnosis >> External Pages >> Different car >> Section 35 (Engine Controls - Self-Diagnostics) >> Diagnostic Tests >> DTC P1656: Oil Control Valve (OCV) Circuit Malfunction >> Diagnosis & Repair (Using Lexus Scan Tool)
April 5, 2026: LEMON Manuals is launched! Read the announcement.

Diagnosis & Repair (Using Lexus Scan Tool)

WARNING: This page is about a different car, the 2002 Lexus GS 300. However, it is still accessible from the selected car via links, so may be relevant.
  1. Start and run engine. Allow engine to reach normal operating temperature. Connect Lexus scan tool to Data Link Connector (DLC) No. 3. See Figure. Select VVT from scan tool ACTIVE TEST menu. Using scan tool, turn OCV on and off. If idle speed is normal with OCV off and engine idles rough or stalls when OCV is on, VVT is functioning properly at this time. Fault is intermittent. DTC may have been set because of a foreign object that was temporarily caught in engine oil system but after a short time system returned to normal. If idle speed does not function as specified, go to next step.
  2. With engine running. Disconnect OCV connector and note idle speed. Engine idle speed should not change. Connect fused jumper wires between positive battery terminal and OCV connector terminal No. 1, and negative battery terminal and OCV connector terminal No. 2. See Figure. Engine should idle rough or stall. If OCV operates as specified, go to next step. If OCV does not operate as specified, replace OCV.
  3. Access ECM at left front of engine compartment. Backprobe ECM E2 connector. Start engine. Backprobing, connect oscilloscope between ECM E2 connector terminals No. 5 (Red/White wire) and No. 6 (White/Red wire). See Figure. Ensure waveform pattern is as illustrated. See Figure. Slowly increase engine speed. Waveform frequency "A" should lengthen as engine speed increases. If waveform pattern is as shown, go to next step. If waveform pattern is not as shown, replace ECM.
  4. Check for an open or short circuit in wire harness or connector between OCV and ECM E2 connector. Repair as necessary. If circuit and connector are okay, problem is intermittent.
scientia non olet · About LEMON Manuals