We received a request to help a shop diagnose a no-start vehicle that was sent to them by a neighboring repair shop. The vehicle was a 2005 Honda Element that would not start after a clutch replacement.
Actually, after the vehicle was towed in, when the shop attempted to start the vehicle, it did start and run, but as soon as they tried to drive into the service bay, the engine stalled.
The shop mentioned when this occurred that the malfunction indicator light (MIL) flashed erratically and became dim. Also, the anti-theft warning light illuminated. Rolling the vehicle back and forth seemed to cause this problem to become sporadic, but the vehicle never ran properly.
Since the transmission had just been removed in order to replace the clutch, a look at the power and ground cables were in order. Inspection of the main ground cable showed it to be connected at the wrong location; also, a mass of electrical tape was wrapped around the middle of the cable. Using a DVOM, we asked the shop to check voltage drop between engine and body while cranking the engine, but no voltage drop was present. Together, we checked all the grounds for voltage drop; again, there was no voltage drop.
After moving the location of the ground, the no-start symptom vanished. The shop could no longer reproduce the symptom. During a road test, the MIL came on and the speedometer did not work. A quick scan found code P0720 for the output shaft speed sensor (OSS), which is also referred to as the vehicle speed sensor (VSS). The wiring to the sensor was checked; power and ground were good. But there was no output signal from the sensor.
Seemed like the problem was found, a faulty sensor. The shop felt confident, they ordered a new sensor and we asked for a follow up to confirm.
Sometimes the trickiest vehicles are the ones with faults so obvious once we locate the root cause.
Information provided by: Autologic Diagnostics
