Diagnostic Aids
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, OVERHAUL & 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 |