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 MANUALSFORD1999MUSTANG GT, 2D CONVERTIBLE, STANDARDREPAIR AND DIAGNOSIS (SINGLE PAGE)EXTERNAL PAGESDIFFERENT CARSECTION 10 (MODULE COMMUNICATIONS NETWORK)SYSTEM TESTSTEST B: CENTRAL SECURITY MODULE DOES NOT RESPOND TO NGS TESTER
1999 Ford Mustang GT, 2D Convertible, Standard
Test B: Central Security Module Does Not Respond To NGS Tester
1999 Ford Mustang GT, 2D Convertible, StandardSECTION Test B: Central Security Module Does Not Respond To NGS Tester
WARNING: This page is about a different car, the 2002 Lincoln Navigator, 2002 Ford Expedition, 2001 Lincoln Navigator, and 2001 Ford Expedition. However, it is still accessible from the selected car via links, so may be relevant.
NOTE:
After making any repair, perform data link diagnostic test. See DATA LINK DIAGNOSTIC TEST under SELF-DIAGNOSTIC SYSTEM.
- Turn ignition switch to LOCK position. Disconnect central security module Black 26-pin harness connector C256. Central security module is located behind left side of instrument panel. Inspect central security module harness connector for loose, damaged or corroded terminals. If problem does not exist with harness connector, go to next step. If problem exists with harness connector, repair as necessary.
- Measure resistance in Light Blue/White wire between central security module harness connector C256 terminal No. 3 and Data Link Connector (DLC) terminal No. 7. See Figure and Fig 1 . If resistance is more than 5 ohms, go to next step. If resistance is 5 ohms or less, go to step 5.
- Disconnect in-line 16-pin harness connector C247. See Fig 2. Inspect both halves of harness connector for loose, damaged or corroded terminals. If problem does not exist with harness connector, go to next step. If problem exists with harness connector, repair as necessary.
- Measure resistance in Light Blue/White wire between central security module harness connector C246 terminal No. 3 and in-line harness connector C247 terminal No. 16. See Fig 1 and Fig 3 . If resistance is 5 ohms or less, repair open in Light Blue/White wire between in-line harness connector C247 and DLC. If resistance is more than 5 ohms, repair open in Light Blue/White wire between central security module and male half of in-line harness connector C247.
- Disconnect all central security module harness connectors. Inspect central security module for loose, damaged or corroded terminals. If problem exists with harness connector, repair as necessary. If problem does not exist with harness connector, connect all central security module harness connectors and retest system. If central security module responds to NGS tester, system is functioning properly. If central security module does not respond to NGS tester, replace central security module. See CENTRAL SECURITY MODULE under REMOVAL & INSTALLATION.
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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.