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 P1520 (Fan_1HI): Radiator Fan Relay 1 Circuit High Input
- Turn ignition off. Connect test mode connector behind left side of dash. Turn ignition on. Using voltmeter connected to ground, backprobe PCM harness connector terminal No. 74 (Red/Blue wire). If voltage reading changes between 0 and 10 volts, system is normal. Check for intermittent open in wiring or connectors. If voltage reading does not change between 0 and 10 volts, go to next step.
- Turn ignition off. Remove main fan relay. On Legacy models equipped with A/C, also remove sub fan relay 1. Disconnect test mode connector. Turn ignition on. Using voltmeter connected to ground, backprobe PCM harness connector terminal No. 74 (Red/Blue wire). If voltage reading is more than 10 volts, repair short to voltage in relay control circuit and replace ECM. If voltage reading is 10 volts or less, check for poor terminal contact in PCM connector. Repair as necessary. If terminal contact is okay, replace PCM.
Factory Service Tools
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
Disclosure: Verified tool recommendations may earn an affiliate commission at no cost to you.
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.
Rather have a pro handle this?
A certified mobile mechanic comes to your home or office. They bring the tools, you stay comfortable. No tow truck, no waiting room, no surprises.
Comes to youSame-day available12-month warranty
Get a Free QuoteNo obligation. See pricing before you book.