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Error Code P0808 is defined as Clutch Position Sensor Circuit High. Error Code P0808 is a generic trouble code, meaning it applies to all vehicles with the OBD-II system, especially those made from 1996 up to present. Specifications on the definition and steps for repairs may vary depending on the model and make of the vehicle.
This includes vehicles from, but not limited to, Chevrolet, Chrysler, Dodge, Ford, Jeep, and Land Rover. Specifications on the definition, troubleshooting, and repairs, of course, vary between make, model, and powertrain configuration.
The clutch position sensor circuit is monitored by the PCM (powertrain control module) or the TCM (transmission control module), based on the specific vehicle. Its job is to monitor the status of the clutch on manual transmission vehicles. It does so by reading the output voltage of the clutch position sensor, which indicates when the clutch is engaged. In most circumstances, it’s basically an on/off switch mounted near the clutch foot pedal on the support bracket. There’s a constant voltage on one side of the switch, and the contacts are closed by engaging the clutch, which transfers voltage to the starter or starter solenoid. The basic circuit and switch keep starting the engine prior to engaging the clutch.
Other codes related to the clutch position sensor circuit include:
When the PCM or TCM detects a voltage or resistance that is higher than expected in the clutch position sensor circuit, then this code will be set. This code will also activate the check engine light or transmission warning lamp.
- Motor unable to start
- Motor starts without engaging the clutch
- Transmission warning lamp activated
- Check engine light activated
- Faulty clutch position sensor
- Damaged or faulty wiring
- Defective or loose control module ground strap
- Defective fuse or fuse-able link (if applicable)
- Corroded, damaged, or loose connector
- Defective PCM or TCM
How to Check
As with most codes, the best way to start your diagnosis with this kind of error code is to refer to a technical service bulletin (TSB) for the specific year, make, model, and power plant of the vehicle. This can save a lot of time in the long run.
Next, find the clutch position sensor switch and search for any signs of physical damage. Check all the wiring associated with the switch and look for signs of burn spots, bare wires, rubbing, and scraping. Next, proceed on checking the connectors and connections for signs of corrosion, damaged pins, or security problems. Make sure you check all the wiring connectors and connections to the clutch position sensor switch, starter and starter solenoid, and PCM. Consult with the specific tech data for the vehicle to see if the fuse or fuse-able link is incorporated into the circuit.
Advanced steps are usually vehicle-specific and may require advanced tools to conduct thoroughly. This includes the use of digital multi-meter and specific technical references for the vehicle. Technical data includes troubleshooting charts and the exact sequence to follow for a more accurate and thorough diagnosis.
If the clutch is disengaged, there should be around 12V on one side of the sensor. If engaged, there should be voltage on both sides. The starter solenoid or starter should also have power on the configuration.
If this can identify the absence of a power source or ground, then conduct a continuity testing to check the integrity of the connectors, wirings, and other components. Make sure you remove the power from the circuit, and the normal readings for the connections and wirings must be at 0 ohms of resistance when conducting a continuity test. Resistance or no continuity means there’s a problem in the wiring (faulty wiring that leads to open or shorted connection). Repair or replace as necessary.
Also, for the PCM or TCM continuity test, control the frame to confirm the serviceability level of ground straps and ground wires. The presence of resistance is an indication of a loose connection or even corrosion.
How to Fix
- Repair or replacement of faulty wiring
- Repair or replacement of blown fuse or fuse-able link (if applicable)
- Cleaning corrosion from connectors
- Repair or replacement of defective ground straps
- Flashing or replacement of PCM or TCM
The severity of this error code is usually normal to moderate. However, in severe cases, the vehicle starts with the clutch disengaged, which can lead to a safety issue.
Make sure you check the clutch position sensor and the wiring to make sure they are not the cause of the problem before replacing the starter, starter solenoid, or control module.