Tach Pulse Signal
- Timing control and triggering of fuel injectors are based upon input signals from TDC/CRANK/CYL sensors. These sensors are simple Permanent Magnet (PM) generator pick-up coils.
- Using a DVOM on low voltage scale (preferably with a bar-graph function), check for a pulsed low-voltage signal at proper Engine Control Module (ECM) harness terminals with engine cranking. See WIRING HARNESS & SENSOR RESISTANCE TEST . See Fig 1 . If a pulsed signal is present, fault does not exist. If pulsed signal is not present, check sensor and wiring integrity.
- To test sensor and wiring integrity, turn ignition off. Disconnect connectors from ECM. Lightly probe appropriate ECM harness terminals to check for proper winding resistance of each sensor. See WIRING HARNESS & SENSOR RESISTANCE TEST . If resistance is within specification, go to step 5). If resistance is not within specification, go to next step.
- Check resistance of TDC/CRANK/CYL sensor directly at sensor connector. See Fig 2 . See TDC/CRANK/CYL SENSOR RESISTANCE TEST . If sensor resistance is within specification, repair open, short or corrosion in wire harness between sensor(s) and ECM. If resistance is not within specification, replace sensor.
- Check continuity to ground at each ECM sensor terminal. If continuity is not present, replace distributor housing. If continuity is present, go to next step.
- Disconnect sensor(s) and recheck for continuity to ground at ECM harness sensor terminals. If continuity no longer exists, go to next step. If continuity to ground is still present, repair short to ground in ECM harness between ECM and sensor(s).
- Check continuity to ground on each sensor connector terminal. See TDC/CRANK/CYL SENSOR RESISTANCE TEST
. See Fig 2
. Continuity should not exist. If continuity to ground exists, replace sensor.WIRING HARNESS & SENSOR RESISTANCE TEST
Application Terminals Ohms Accord F22B1 Engine CRANK B15 & B16 700-1300 CYL B11 & B12 700-1300 TDC B13 & B14 700-1300 F22B2 Engine CRANK B15 & B16 350-700 CYL B11 & B12 350-700 TDC B13 & B14 350-700 Prelude CRANK B15 & B16 350-700 CYL B11 & B12 350-700 TDC B13 & B14 350-700 Odyssey CRANK B8 & B16 700-1300 CYL B7 & B15 700-1300 TDC B6 & B14 700-1300 TDC/CRANK/CYL SENSOR RESISTANCE TEST (1)Application Terminals Wire Color CRANK Sensor Wire 1 Of 2 "B" Blue/Green 2 Of 2 "F" Blue/Yellow CYL Sensor Wire 1 Of 2 "D" Orange 2 Of 2 "H" White TDC Sensor Wire 1 Of 2 "C" Orange/Blue 2 Of 2 "G" White/Blue (1) CRANK/CYL/TDC sensors are located inside distributor assembly.