Overhead Control Panel (OCP) (N70)
Overhead Control Panel (OCP) (N70)
The Overhead Control Panel (OCP) (N70) is located in the roof console area. It contains one circuit board which includes lighting control, sunroof control, and the inside air temperature sensor used by the Automatic Climate Control (ACC).
The OCP contains:
- Air Temperature Sensor / Thermistor (N70/b1), which measures cabin air temperature near the roof.
- Aspirator fan, which draws cabin air across the temperature sensor.
- Electrical connectors for the overhead control panel functions.
The ACC also uses another in-cabin air temperature sensor in the Pushbutton Control Module (N22). Testing methods for the OCP (N70) are very similar to the testing methods for the Pushbutton Control Module (N22).
Removal of Overhead Control Panel
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- Remove the two light lenses (1) by prying from the rear.
- After removing the lenses, two or four steel clips will be visible, depending on model. These clips hold the OCP (N70) in place.
- Pry the steel clips towards the center of the unit. The OCP should drop down slightly as each clip is released.
- Continue working around the unit until the last tab is released and the OCP can swing down. WIS says to press the clips in the direction of the arrows and swing the overhead control panel control module (N70) down.
- Disconnect the electrical connectors and connections (2).
- The two largest connectors are locked in place by levers. Press the tab and move the levers down; the connectors should then come out easily.
- The smaller wire connectors are friction-fit only.
- Reinstall in the opposite order.
- TIP: Before installing the OCP, check the position and number of cables routed through the cable clamp.
Electrical Connector Warning
Warning: one of the OCP electrical connectors can be difficult to reinstall correctly. If it is not seated properly it may cause fault codes and malfunctions which can be difficult to diagnose.
If the OCP is removed and the four or five electrical plugs are disconnected, depending on model, pay special attention during reinstallation to the second plug from the left. This plug has a light gray swing clip which is pulled to the left to slide the plug out.
When reconnecting this plug, do not simply push the plug in and move the lever back to the right. It may look and feel connected, but it may not be fully seated.
The correct installation is to push the second plug in until it clicks, then pull the lever back to the right to lock it in place. On the black part of the plug there is a half-circle track that the light gray clip follows. The left side of that half-circle must be right up against the module being plugged into.
If this connector is not seated properly, the vehicle may display the warning Light Sensor Visit Workshop. The headlights may remain on in AUTO mode regardless of whether it is day or night, the automatic headlight delayed shut-off may stop working, and the lights may turn off immediately when the key is switched off. The rain-sensing wipers may also stop working correctly in the first click position and instead behave like intermittent wipers, wiping about every five seconds regardless of rain intensity.
Dismantling of Overhead Control Panel
Once the OCP is removed and placed on a clean work bench, it can be dismantled to access the aspirator fan and the thermistor temperature sensor.
- Remove the light bulbs.
- Remove the back cover by removing the nine Torx screws.
- Remove the circuit board by pushing it out of the housing.
- Reinstall in reverse order.
Replacing In-Cabin Air Temperature Sensor
The ACC Air Temperature Sensor (N70/b1) in the OCP often fails and can cause ACC malfunction. The sensor is a thermistor located in the center of the mini aspirator fan. It measures cabin air temperature near the roof, while the aspirator draws cabin air across it.
The sensor can be diagnosed using the ACC Hidden Menu Feature. See Automatic Climate Control (ACC) Service Menus. Check the ACC actual value:
Parameter NR.01: In Car Temperature Sensor (N70/b1), ACC Overhead Control Panel (OCP) (N70)
This value should show the cabin air temperature near the roof of the vehicle, for example about 20-30C depending on conditions. If it reads 0C or 63C, there is likely a fault.
The sensor resistance can also be tested directly. At approximately 20C, the thermistor should measure around 10k ohms.
The OCP has one circuit board which includes lighting control, sunroof control, and the inside temperature sensor. The thermistor is connected by thin wires which are melted into the fan housing. These wires are brittle and are often found broken, causing ACC issues.
The thermistor leads can break because they run close to the fan and may come into contact with it. They can also fail from fatigue caused by micro-motion of the fan cover, corrosion of the leads, or a combination of these factors.
If the wires are intact, they must be unsoldered from the printed circuit board before removing the fan shroud with the thermistor still inside it. This is difficult, so it is often easier to cut the wires halfway along their vertical length and solder in the replacement thermistor.
During reassembly, thoroughly clean any dust from the aspirator motor and thermistor housing.
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Resistance Specification
Refer to ACC and HVAC for resistance specification of temperature sensors. This resistance specification applies to both in-cabin air temperature sensors, even though their appearance is not identical:
- Sensor N22/b1, located in the Pushbutton Control Module (N22).
- Sensor N70/b1, located in the Overhead Control Panel (N70).
Aftermarket sensor with close specifications:
- VISHAY NTCLE100E3103HB0 (NTC thermistor; 10kΩ; THT; 3977K; -40÷125°C; 500mW)
Aspirator
Inside the OCP is an aspirator fan which draws cabin air over the temperature sensor. This reading is used by the ACC to help regulate cabin temperature. A similar air sampling function is also used by the ACC Pushbutton Control Module.
Before disconnecting the OCP wiring, the aspirator fan can be checked with the OCP dropped down. Turn the ignition to the ON position and use a flashlight to look through the opening at the end of the unit. The fan should be visible spinning.
A common issue is a rattling aspirator housing. The fan shroud is clipped to the fan base and is slightly loose by design, so it may move with very little force. To stop the rattle, dismantle the OCP and apply four small blobs of silicon adhesive, one at each corner of the fan shroud, to secure it to the printed circuit board.
Do not spray silicone, Teflon, or other lubricant through the ventilation slots to quieten the aspirator. The blower is self-lubricated, and added lubricant may only quieten it temporarily while causing dust to accumulate. This can eventually clog the aspirator and require replacement. If the sensor or aspirator is dirty, dismantle the OCP and clean the sensor, aspirator motor, and thermistor housing.