1998 Saturn SC1 shifting problems

RICKFULLMER

MEMBER
1998 SATURN SC1
4 CYL
FWD
AUTOMATIC
11,500 MILES

When driving at highway speeds the car will shudder at 55 mph to 60 mph. It seems that it will not down shift from overdrive. I either shift through the gears from low to drive or I force the accelerator detent to come out of the hesitation. I suspect a torque converter solinoid having a problem. Also I have a check engine light with an O2 sensor problem. Scan code fault states cat converter efficency problem, but the exhaust pressure is good and the car runs good.

Thursday, November 13th, 2008 AT 3:12 AM

1 Reply

DAVE H

MECHANIC
13,384 POSTS

DESCRIPTION & OPERATION
Saturn vehicles use a 4-speed, fully automatic, electronically controlled transaxle with shift mode select function and self-diagnostic function.
The transaxle uses 5 electronic valves (line actuators), controlled by the Powertrain Control Module (PCM). The PCM controls all transaxle shifts, shift feel, Torque Converter Clutch (TCC) lock-up and self-diagnostics. PCM is located behind right side of dash. PCM has two 32-pin connectors and two 24-pin connectors.
If an electrical circuit or component problem occurs, MALFUNCTION INDICATOR LIGHT (MIL) may illuminate or start flashing. PCM will store Diagnostic Trouble Codes (DTC's) in memory. A stored DTC indicates PCM has detected a fault in engine or transaxle circuits or components.
PCM is capable of operating in 2 different modes. The differences between the 2 modes are shift points. NORMAL mode or PERFORMANCE mode may be selected using mode switch. Mode switch is located on center console.

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Thursday, November 13th, 2008 AT 8:16 AM