Fuel Injection System - Diesel: Testing: MVS
- Allow engine to warm up. Shut off engine. Remove air cleaner cover. Place MAP sensor with leads and vacuum hose attached aside. Remove air crossover and install covers. Disconnect HPAA solenoid lead and MVS harness.
- Install MVS Test Harness (J-34678) and MVS Adapter Harness (J-64678-50) (Not needed on C series with internal EGR). Install tachometer. Start engine. Set parking brake and shift into "D". With alternator connected, set idle to 600 RPM (all V8), 675 (C Series with external EGR), 650 all others.
- Set a multi-meter at the 20 volt scale and measure voltage between terminals "A" and "C". See Fig 1
or Fig 2
. This is V-Ref. Record this reading. Measure between terminals "B" and "C". This is the MVS voltage for the given engine load. Record this reading. Shift transmission to "P". Compare voltages recorded with the chart below.
MVS Voltage Table
| V-Ref |
MVS Voltage |
| 4.0 |
.47-.49 |
| 4.1 |
.48-.50 |
| 4.2 |
.49-.51 |
| 4.3 |
.50-.52 |
| 4.4 |
.51-.54 |
| 4.5 |
.53-.55 |
| 4.6 |
.54-.56 |
| 4.7 |
.55-.57 |
| 4.8 |
.57-.59 |
| 4.9 |
.58-.60 |
| 5.0 |
.59-.61 |
| 5.1 |
.60-.62 |
| 5.2 |
.61-.63 |
| 5.3 |
.63-.65 |
| 5.4 |
.64-.66 |
| 5.5 |
.65-.67 |
- Shift into "D"and measure voltage between terminals "B" and "C" while throttle is moved quickly from idle to nearly full throttle. Voltage should go from less than 1 volt to over 4. If not, MVS must be adjusted. See Adjusting the MVS in this article.