What this code means
P0843 concerns the voltage signal from the CVT driven pulley pressure sensor. The transmission control module, or TCM, can store this code when that signal is higher than the specified value.
Work through the checks in order. Start by checking the sensor reading with the HDS diagnostic tool. Then check voltage at the disconnected sensor connector. The later checks examine the three wires between the sensor and the TCM.
What the vehicle may do
The sensor signal may be too high, and the TCM may store P0843. The checks below help establish whether that high reading is present and whether the results point to the sensor, a related circuit, or the TCM.
Possible fault areas
- The CVT driven pulley pressure sensor.
- The VCC4 power-supply circuit, PDN signal circuit, or SG4 ground circuit.
- The TCM.
Keep these circuit names available as you work. Each wire has its own pair of connector terminals, so the resistance checks must stay matched to the correct terminals.
Diagnostic path
Check whether the high sensor reading is present
Set the vehicle to ON mode. On the HDS, open the AT Data List and find the reading called Driven Pulley Pressure Sensor(V).
Read the displayed voltage. If it is more than 4.84 volts, the failure is duplicated.
This is the initial fault-confirmation reading. The connector voltage checks below use a different expected reading, about 5 volts, with the sensor connector disconnected.
Check voltage between sensor connector terminals 1 and 3
The sensor is assessed indirectly through its related components. The two connector voltage readings are taken with the sensor unplugged.
Disconnect the CVT driven pulley pressure sensor connector (3P). For this measurement, IG Mode must be ON, and the connector remains disconnected.
Measure voltage at the female terminals of that connector. Put one probe on terminal 1 and the other on terminal 3. A normal reading is about 5 volts.
Record this result before moving to the next measurement. This check uses two terminals of the same disconnected sensor connector.
Check voltage between sensor connector terminal 2 and ground
Keep the sensor connector (3P) disconnected and keep IG Mode ON.
Move one probe to female terminal 2 of the sensor connector. Place the other probe on ground. A normal reading is about 5 volts.
The probe locations are different from the previous check. Here the measurement is between terminal 2 and ground, rather than between terminals 1 and 3.
Use the two voltage results
If these voltage checks are normal, the checks point to a problem with the driven pulley pressure sensor. If the results are abnormal, the problem is in other related components.
The wire checks below examine the VCC4, PDN, and SG4 circuits individually. Keep each reading linked to the circuit and terminal pair used for that check.
Prepare for the wire checks
Before disconnecting the TCM connector, use the HDS to jump the SCS line. Wait more than 1 minute before disconnecting the TCM connector.
For the wire checks, disconnect both the TCM connector (50P) and the CVT driven pulley pressure sensor connector (3P). Perform the resistance measurements with IG Mode OFF and both connectors disconnected.
The following measurements are resistance checks between the two disconnected connectors. They are separate from the earlier voltage checks, which used IG Mode ON.
Check the VCC4 power-supply wire
With IG Mode OFF and both connectors disconnected, measure resistance between these female terminals.
- TCM connector (50P), terminal 17.
- CVT driven pulley pressure sensor connector (3P), terminal 3.
A normal reading is less than 1 ohm. Record the result as the VCC4 wire check.
Check the PDN signal wire
Keep IG Mode OFF and both connectors disconnected. Measure resistance between these female terminals.
- TCM connector (50P), terminal 31.
- CVT driven pulley pressure sensor connector (3P), terminal 2.
A normal reading is less than 1 ohm. Record the result as the PDN wire check.
Check the SG4 ground wire
Keep IG Mode OFF and both connectors disconnected. Measure resistance between these female terminals.
- TCM connector (50P), terminal 29.
- CVT driven pulley pressure sensor connector (3P), terminal 1.
A normal reading is less than 1 ohm. Record the result as the SG4 wire check.
Use the wire-check results
If a VCC4, PDN, or SG4 wire check is abnormal, there is a problem in that circuit. Use the individual results to identify which circuit is affected.
The final TCM branch applies when all the other checks are normal. Under that condition, the TCM is identified as the cause.
Final check
Review the results with their test conditions. The initial HDS check uses more than 4.84 volts to confirm the failure. The two disconnected-sensor connector checks use about 5 volts with IG Mode ON. Each wire resistance check uses less than 1 ohm with IG Mode OFF and both connectors disconnected.
Keep the sensor, circuit, and TCM conclusions tied to the corresponding results. In particular, apply the final TCM conclusion only when all the other checks are normal.
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