9-3 Viggen Coupe (9400) L4-2.3L Turbo (B235) HO (1999)
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When shifting up or down, the control module receives the signal on pin 51 from the automatic transmission control module pin 13.
Depending on the load and speed of the engine, the voltage drops on pin 51 from B+ to 0 Volts in a very short time (max 250 ms).
When the control module receives this information, it retards the ignition to be able to reduce the engine torque.
When maximum engine load occurs the ignition can be retarded to 0° or more (minus).
If the signal is missing, the CHECK ENGINE lamp (MIL) comes on and in addition it can cause "coarser" gear shifts
