Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
1998 Subaru Forester BaseFACTORY OEM SERVICE PROCEDURE
DTC P1103 (TRQ): Engine Torque Control Signal Circuit Malfunction
- Turn ignition on. Using voltmeter connected to ground, backprobe PCM connector terminal No. 79 (Pink wire on Forester and Impreza, or Blue wire on Legacy). If voltage reading is more than 4.5 volts, check PCM connection. Repair as needed. If connection is okay, replace PCM. If voltage reading is 4.5 volts or less, go to next step.
- Turn ignition off. Disconnect connectors from TCM and PCM. Using an ohmmeter, check resistance between TCM connector terminal No. 16 and ECM connector terminal No. 79 (Pink wire on Forester and Impreza, or Blue wire on Legacy). If resistance is one ohm or less, go to next step. If resistance is more than one ohm, repair open in harness between TCM and PCM.
- Check resistance between PCM connector terminal No. 79 and ground. If resistance is 10 ohms or less, repair short to ground in harness. If resistance is more than 10 ohms, check TCM connection. Repair as needed. If connection is okay, replace TCM.
Factory Service Tools
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.
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