Diagnostic Aids
WARNING: This page does not describe the selected car, but rather 32 other vehicles, including the 2003 Mercury Sable, 2003 Mercury Mountaineer, 2003 Mercury Marauder, 2003 Mercury Grand Marquis, and 2003 Lincoln Town Car. However, it is still accessible from the selected car via links, so may be relevant.
Perform this test when directed by QUICK TEST or if directed by other test procedures. This test is used to diagnose:
- HO2S Heater
- Engine Vacuum Systems
- Fuel Injector(s)
- Wiring Harness Connector & Circuits; (HO2S HTR, INJ 1-8, VPWR & SIG RTN)
- Powertrain Control Module (PCM)
- Natural Gas (NG) Module
WARNING:
Fuel system remains under high pressure even when engine is not running. To avoid injury, release fuel pressure before disconnecting any fuel system hose or component. See appropriate FUEL SYSTEM PRESSURE RELEASE procedure under FUEL SYSTEM VENTING in appropriate REMOVAL & INSTALLATION article.
NGV HO2S PCM TERMINAL IDENTIFICATION
| Application | PCM Terminal No. |
|---|---|
| HO2S-11 SIG (Right Upstream) | 60 |
| HO2S-11 HTR (Right Upstream) | 93 |
| HO2S-12 SIG (Right Downstream) | 35 |
| HO2S-12 HTR (Right Downstream) | 95 |
| HO2S-21 SIG (Left Upstream) | 87 |
| HO2S-21 HTR (Left Upstream) | 94 |
| HO2S-22 SIG (Left Downstream) | 61 |
| HO2S-22 HTR (Left Downstream) | 96 |
| HO2S SIG RTN | 91 |
| HO2S VPWR | 71 |
For HO2S connector terminals, see Figure.