A Hyundai equipped with an A4CF2 may come into the shop in third-gear failsafe with the “Check Engine” lamp illuminated. Code retrieval may produce a number of solenoid or ATF-temperature-sensor codes (Figure 1).

The internal wire harness (Figure 2), commonly referred to as the “ribbon,” has failed. Faulty solenoids or temperature sensor also could cause any of the codes listed in Figure 1. External wiring and the TCM are also included in the equation, since any component in the circuit could generate a code. In addition, there have been reports of the vehicle-harness connector end creating these complaints.

Diagnose the solenoid circuits for which there are codes, bearing in mind that both the “ribbon” and the vehicle-harness connector are common failure items.

• Solenoid internal wire harness (ribbon) . . . . . 46308-23000
• VFS solenoid (1). . . . . . . . . . . . . . . . . . . . . . . . . . . . 46313-23010
• ATF-temperature internal wire harness . . . . . . 46307-23010

After an overhaul, a Nissan/Infiniti vehicle equipped with the RE4F04B may exhibit a complaint of no turbine-sensor reading on a hand-held scan tool.

One cause may be an incorrect forward/coast-clutch housing installed in the transmission during the overhaul.

Unlike the RE4F04A, the RE4F04B transmission additionally uses a turbine-speed sensor along with the output-speed (revolution) sensor. The combination of the two sensors helps the computer to more accurately recognize input and output speeds, which results in improved shifting characteristics and optimum shift timing during deceleration. Figure 3 shows the location of the turbine-speed sensor.

With the addition of the turbine-speed sensor it was necessary to change the forward/coast-clutch housing. The forward/coast-clutch housings for the RE4F04A and RE4F04B look very similar; however, the lugs on the outside of the drum were increased in length to provide a surface for the turbine-speed sensor to obtain its reading. The partial-cutaway diagrams in Figure 4 show how the turbine-speed sensor can read the forward/coast-clutch housing with the RE4F04B drum installed, and how the turbine-speed sensor is unable to read the forward/coast-clutch housing with the RE4F04A drum installed.

Use the correct forward/coast-clutch housing for the application you are working on. The two illustrations in Figure 5 show the differences between the forward/coast-clutch housings. The RE4F04B that is equipped with a turbine-speed sensor has lugs that measure about 3.187 inches in length. The RE4F04A that IS NOT equipped with a turbine-speed sensor has lugs that measure about 2.863 inches in length.

Before or after an overhaul, a Nissan/Infiniti vehicle equipped with the RE5F22A exhibits a failsafe condition consisting of 5th-gear starts with DTC P0726, “Engine speed signal fault,” stored in TCM memory.

The cause may be a faulty crankshaft-position sensor or faulty camshaft-position sensor. The engine-speed signal on these vehicles is a calculated value based on input from the crankshaft-position sensor (POS) and camshaft-position sensor (phase) Bank 1 and camshaft-position sensor (phase) Bank 2. The engine-speed signal is computed by the ECM and sent via the CAN system to the transmission control module (TCM). A quick look at the chart in Figure 6 will show the different input/output signals for TCM function. As shown by the chart, if the engine-speed-signal input is problematic, the TCM will default the vehicle into fail-safe-mode fifth gear.

To correct this issue it will be necessary to determine which sensor or combination of sensors may be contributing to the problem. Connect a capable scan tool to read the ECM fault codes. See whether any of the following DTCs are stored.

• Crankshaft-position sensor; P0335 CKP sensor (POS)
• Camshaft-position sensor; P0340 CMP sensor (phase)
• Camshaft-position sensor; P0345 CMP sensor (phase)

Typically if a DTC is stored for one of these components, replacement of the offending sensor usually corrects the issue. However, it may be necessary to check the individual sensors using a DVOM and/or a graphing meter or scope to monitor the signal in the event that the sensor hasn’t failed completely.

• For DTC P0335 CKP sensor (POS) proceed to DTC P0335 check.
• For DTC P0340 CMP sensor (phase) proceed to DTC P0340 check.
• For DTC P0345 CMP sensor (phase) proceed to DTC P0345 check.

DTC P0355 check

The crankshaft-position sensor CKP (POS) is used to detect engine revolution. When the engine is running, the sensor magnet detects the peaks and valleys of the reluctor, then inputs a digital signal to the ECM. This signal can be seen on a hand-held scan tool in the form of an rpm reading that should be very similar to the tachometer reading. A DTC for the CKP (POS) may be detected under the following conditions:

1. Crankshaft-position-sensor signal is not detected by the ECM during the first few seconds of engine cranking.
2. The proper pulse signal from the crankshaft-position sensor is not detected by the ECM while the engine is running.
3. The crankshaft-position-sensor signal pattern detected is abnormal while the engine is running.

The diagram in Figure 7 illustrates the wiring and pin configurations for the CKP (POS) in a 2005 Nissan Maxima and is typical. For correct wire color and pin numbers, refer to the appropriate factory manual for the vehicle you are working on. Verify correct voltage input to the CKP (POS) sensor (system voltage with key on/engine running at pin 3) of the sensor and verify that sensor has a good ground (less than 0.1 volt DC key on/engine running at pin 1). Once this has been verified, hook up an appropriate graphing meter or oscilloscope and verify the pulsed signal output to the ECM.

Figure 8 shows a sample pattern of the pulsed signal.

DTC P0340 – DTC P0345 check

The camshaft-position sensors CMP 1 and CMP 2 (phase) are used to detect the rotation of the camshaft to identify a particular cylinder and to recognize piston position. When the engine is running, the sensor magnet detects the peaks and valleys of the reluctor, then inputs a digital signal to the ECM. If the crankshaft-position sensor (POS) system fails or is determined to be inoperative, the camshaft-position-sensor (phase) signal is used to provide various controls of engine function instead, using the timing of cylinder-identification signals. A DTC for the CMP 1 and CMP 2 (phase) may be detected under the following conditions:

1. The cylinder-identification signal is not detected by the ECM during the first few seconds of engine cranking.
2. The proper cylinder-identification signal is not detected by the ECM while the engine is running.
3. The cylinder-identification-signal pattern detected is abnormal while the engine is running.

Figure 9 illustrates the wiring and pin configurations for the CMP (phase) in a 2005 Nissan Maxima and is typical. For correct wire color and pin numbers, refer to the appropriate factory manual for the vehicle you are working on. Verify correct voltage input to CMP (phase) Bank 1 and CMP (phase) Bank 2 (system voltage with key on/engine running at pin 3) of sensor CMP (phase) Bank 1 and CMP (phase) Bank 2 and verify that each sensor has a good ground (less than 0.1 volt DC key on/engine running at pin 1) of sensor CMP (phase) Bank 1 and CMP (phase) Bank 2.

Once this has been verified, connect an appropriate graphing meter or oscilloscope and verify the pulsed signal output to the ECM from the related sensor terminal. Figure 10 shows a sample pattern of the pulsed signal.

May 2012 Issue
Volume 29, No. 5

• Hyundai A4CF2: solenoid codes
• Nissan/Infiniti RE4F04B: no turbine-speed-sensor reading
• Nissan/Infiniti RE4F22A: failsafe with DTC P0726