Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Vehicle Speed Sensor: MDX
2004 Acura 3.5RLSECTION MDX
NOTE:
Before troubleshooting Vehicle Speed Sensor (VSS), connect scan tool to DLC and check for stored DTC P0721. If present, go to DTC P0721: COUNTERSHAFT SPEED SENSOR CIRCUIT RANGE/PERFORMANCE PROBLEM in appropriate DIAGNOSTICS article in AUTOMATIC TRANSMISSIONS.
- Check No. 9 (10-amp) fuse in driver's underdash fuse/relay box. Check for continuity between instrument panel gauge assembly 14-pin harness connector terminals No. 9, 10 and ground connector terminal G501 located at lower left center of dash (both Black wires). Repair as necessary. If continuity is present in both wires, go to next step.
- Raise and support front of vehicle. Disconnect 14-pin harness connector from instrument panel gauge assembly. Connect negative probe of DVOM to ground and positive probe to gauge assembly 14-pin harness connector terminal No. 2 (Blue/White wire). Place A/T in Neutral and turn ignition switch on. While observing voltmeter, slowly rotate one wheel (more than 3 mph) with opposite wheel blocked. If voltage does not pulse between zero and about 5 volts, turn ignition switch off and go to next step. If voltage pulses between zero and about 5 volts or more, replace speedometer or printed circuit board.
- Turn ignition switch off. Disconnect PCM harness connector B. See Fig 1 . Check for continuity in Blue/White wire between gauge assembly 14-pin harness connector terminal No. 2 and PCM harness connector B terminal No. 26. If continuity is present, go to next step. If continuity is not present, repair open in Blue/White wire between gauge assembly 14-pin harness connector terminal No. 2 and PCM harness connector B terminal No. 26.
- Disconnect driver's multiplex control unit connector B, multi-information display unit connector B (w/o navigation), or navigation unit connector C (w/navigation), climate control unit connector B, and the driver's power seat control unit connector "A". See Fig 2 . Check for continuity between ground and PCM harness connector B terminal No. 26. If continuity is present, repair short to ground in Blue/White wire between PCM harness connector B terminal No. 26, driver's multiplex control unit connector B, multi-information display unit connector B (w/o navigation), or navigation connector C (w/navigation), climate control connector B, and the driver's power seat control unit connector "A". See appropriate wiring diagram under ENGINE PERFORMANCE in WIRING DIAGRAMS. If continuity is not present, check for bent, loose or corroded terminals. If all connectors are okay. Substitute known-good PCM, then recheck. If symptom or indication goes away, replace original PCM.
RENDER: 1.0x
NO RELATED
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.