Turbocharger - Will Not Exceed Base Boost Pressure
85saab03FILE IN S.I. Man. VOL. I
SEC. A-3 PG. 94
Service Information
SUBJECT: POSSIBLE ELECTRICAL FAULT ISSUE: 12/85-812 GIVING LOW BOOST PRESSURE
APPLICATION: 1986 900 TURBOS
Beginning with M86 900 Turbos a feature was added to the APC control system which reverts the boost pressure to base boost when the brakes are applied. This function is achieved by wiring pin No. 20 of the APC unit to the brake light switch. When 12V is applied (as when depressing the brake pedal) to pin No. 20, the system will only allow base boost. This feature was added to prevent unnecessary strain on the brakes when making a boost test.
A limited number of early Turbos may have been built with the wire from pin No. 20 mistakenly connected directly to the 12V constant voltage side of the brake light switch. Should you have a complaint that a Turbo will not exceed base boost, check the connections at the switch and, if necessary, change the connection from the constant side to the switched voltage side.
To repair (if connected improperly at factory), the technician must cut the white wire from the "hot" side of switch (circuit #131) and splice into the brake light side of switch (circuit #132).
Warranty Information: For Warranty claims, use Failure Code 36430-01-0-01-05. Time to check and correct the connection is 0.4 hour, to be entered as Straight Time. ($10 claim minimum applies.)