| Test | TECH 1 | Notes | Nominal Values | Pin | Possible |
|---|---|---|---|---|---|
| Step | Display | Trouble | |||
| No. | Codes | ||||
| 20 | IAC BLOCK LEARN | Engine at idle speed, | 75 to 175 steps | - | - |
| operating temperature | 128 steps | ||||
| Without odometer frequency sensor |
Note:
This test step is not active on the C 24 NE, MY '89. If there are idling problems, carry out test steps 14 and 18.
The IAC BLOCK LEARN gives the nominal air requirements of the engine.
Via the IAC BLOCK LEARN, evaluation of the learned values of the system can be made after a journey (speed influence).
The IAC BLOCK LEARN is only activated if a speed signal is received from the control unit.
(A precondition is an installed odometer frequency sensor)
Odometer frequency sensors are only installed in conjunction with the board computer, radio SC 804 and LCD instrument.
On vehicles without odometer frequency sensor, the value must constantly be 128.
Trouble-shooting: Nominal Value: Cause of Fault:
(If nominal value is not attained)
Value < 75 steps
· Air loss (leaks) at · Lack of air
throttle valve connection, intake - Idle speed adjuster jams, does not close
system, bypass lead - Bypass air hose blocked or
kinked
· Throttle valve open, - Carry out F5:ACTUATOR TEST,
accelerator cable or throttle valve jams test step 01
· Idle speed adjuster jams, does not close · Control unit defective
Carry out F5:ACTUATOR TEST, (test see table 5 F5:ACTUATOR TEST,
test step 01 test step 01)