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.
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HOMESERVICE MANUALSMERCURY1991TRACER BASE, 4D SEDAN, AUTOMATICREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 3 (ENGINE CONTROLS - TESTS W/CODES - EEC)CIRCUIT TESTSCIRCUIT TEST SCG - SOLENOID CONTROLLED BY GROUNDSWITCH PERFORMANCE CHECK
1991 Mercury Tracer Base, 4D Sedan, Automatic
Switch Performance Check
1991 Mercury Tracer Base, 4D Sedan, AutomaticSECTION Switch Performance Check
WARNING: This page is about a different car, the 1992 Mercury Tracer, 1992 Ford Probe, and 1992 Ford Escort. However, it is still accessible from the selected car via links, so may be relevant.
To properly diagnose solenoid, it must be checked in the ON and OFF positions. When test procedure requires click test, check appropriate solenoid as follows.
- BOOST
Install breakout box, leaving ECA disconnected. Turn ignition
- Apply pressure to vacuum nipple of turbocharger boost control solenoid. Using jumper wire, ground the BOOST test pin of breakout box to release vacuum.
- CANP
Install breakout box, leaving ECA disconnected. Turn ignition
- Apply vacuum to vacuum nipple of canister purge solenoid. Using jumper wire, ground CANP test pin of breakout box to release vacuum.
- EGRC/EGRV
Install breakout box, leaving ECA disconnected. Turn ignition
- Apply vacuum to EGR valve. Vacuum should not hold. Using jumper wire, ground appropriate test pin of breakout box. See CIRCUIT PIN IDENTIFICATION (SCG) . Apply vacuum to EGR valve. Vacuum should hold.
- HSIA
Install breakout box, leaving ECA disconnected. Turn ignition
- Apply vacuum to HSIA solenoid. Vacuum should hold. Using jumper wire, ground No. 53 test pin of breakout box. Vacuum should release.
- PRC
Install breakout box, leaving ECA disconnected. Turn ignition
- Apply vacuum to PRC solenoid. Vacuum should hold. Using jumper wire, ground appropriate test pin of breakout box. See CIRCUIT PIN IDENTIFICATION (SCG) . Vacuum should release.
- ISC
Install breakout box, leaving ECA disconnected. Turn ignition
- Using jumper wire, ground No. 41 test pin of breakout box. ISC solenoid should click when test pin is grounded.
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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.