Pontiac Fiero 1988 Service Manual page 701

6E3-C8-4 DRIVEABILITY AMD EMISSIONS - FUEL INJECTION (PORT)
ECM
AUTO TRANSMISSION
(125 C)
5-26-87
5-8-87
7S3376-6E
CHART C-8A
125C TRANSMISSION/TRANSAXLE CONVERTER CLUTCH (TCC)
( E L E C T R I C A L D I A G N O S I S )
2.8L " P" SERIES (PORT)
Circuit Description:
The purpose of the transmission converter clutch feature is to eliminate the power loss of the transmission
converter stage when the vehicle is in a cruise condition. This allows the convenience of the automatic
transmission and the fuel economy of a manual transmission.
Fused battery ignition is supplied to the transmission/transaxle converter clutch (TCC) solenoid through
the brake switch, and transmission third gear apply switch. The electronic control module (ECM) will engage
TCC by grounding CKT 422 to energize the solenoid.
TCC will engage when:
• Engine warmed up
• Vehicle speed above a calibrated value (about 32 mph 51 km/h).
• Throttle position sensor output not changing, indicating a steady road speed.
• Transmission third gear switch closed
• Brake switch closed
Test Description:
Numbers below refer to circled
numbers on the diagnostic chart.
Diagnostic Aids:
i.
2.
Light "OFF" confirms transmission third gear
apply switch is open.
At 25 mph the transmission third gear apply
switch should close. Test light will come on and
confirm battery supply and closed brake switch.
Grounding the diagnostic terminal with ignition
"ON," engine "OFF" should energize the TCC
solenoid by grounding CKT 422. This test checks
the capability of the ECM to supply a ground to
the TCC solenoid. The test checks the ability of
the ECM to supply a ground to the TCC solenoid.
The test light connected from 12 volts to assembly
line data link (ALDL) terminal "F" will turn "ON"
as CKT 422 is grounded.
A "Scan" tool only indicates when the ECM has
turned on the TCC driver, and this does not confirm
that the TCC has engaged. To determine if TCC is
functioning properly, engine rpm should decrease
when the "Scan" indicates the TCC driver has turned
"ON".