SYS.OK|MANUAL.DB● LIVE
HOMESERVICE MANUALSCHEVROLET1998SUBURBAN K2500, 7.4 J, PART TIMEREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 24 (ENGINE CONTROLS - TESTS W/CODES - 6.5L)DIAGNOSTIC TROUBLE CODESDTC P0370 - TIMING REFERENCE HIGH RESOLUTIONDIAGNOSTIC PROCEDURES
1998 Chevrolet Suburban K2500, 7.4 J, Part Time

Diagnostic Procedures

1998 Chevrolet Suburban K2500, 7.4 J, Part TimeSECTION Diagnostic Procedures
WARNING: This page does not describe the selected car, but rather 10 other vehicles, including the 1997 GMC Yukon, 1997 GMC Suburban, 1997 GMC Pickup, 1997 GMC Cab & Chassis, and 1997 GMC C3500 HD. However, it is still accessible from the selected car via links, so may be relevant.
  1. Perform Powertrain ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK. See the BASIC TESTING - 6.5L DIESEL article. Then go to next step.
  2. Turn ignition off. Disconnect optical/fuel temperature sensor connector. Turn ignition on, with engine off. Using DVOM, check voltage between 5-volt reference circuit of optical sensor connector and ground. If voltage is 5 volts, go to next step. If voltage is not 5 volts, go to step 5).
  3. Using a test light connected to battery voltage, probe ground circuit of optical sensor connector. If test light illuminates, go to next step. If test light does not illuminate, go to step 8).
  4. Reconnect optical/fuel temperature sensor connector. Start and idle engine. Using scan tool, command engine speed to 900 RPM. Using DVOM on Hz scale, backprobe high resolution signal circuit of PCM. If DVOM reading is 3740-3940 Hz, go to step 11). If DVOM reading is not 3740-3940 Hz, go to step 10).
  5. If vehicle is equipped with an electrical filter harness at the optical sensor, go to next step. If vehicle is not equipped with and electrical filter, go to step 7).
  6. Remove electrical harness filter from vehicle. Using DVOM, check resistance of filter. If resistance is greater than 2 ohms, go to step 14). If resistance is less than 2 ohms, go to next step.
  7. Turn ignition off. Leave electrical harness filter removed from vehicle. Disconnect PCM harness connector. Check 5-volt reference circuit for open, short to ground, or short to sensor ground circuit. Repair as necessary. After repairs, go to step 15). If circuit is okay, go to step 9).
  8. Check for open or poor connections at sensor ground terminals of PCM. Repair as necessary. After repairs, go to step 14). If connections are okay, go to step 12).
  9. Check for poor connections at 5-volt reference terminals of PCM. Repair terminals as necessary. After repairs, go to step 15). If terminals are okay, go to step 13).
  10. Turn ignition off. Check for open or short to ground in high resolution signal circuit. Repair as necessary. After repairs, go to step 15). If circuit is okay, go to step 12).
  11. Check for poor connections at high resolution signal terminals of PCM. Repair terminals as necessary. After repairs, go to step 15). If terminals are okay, go to step 13).
  12. Replace injection pump. If fuel injection pump is replaced, new pump must be timed. See the ADJUSTMENTS - 6.5L DIESEL article. After replacing injection pump, go to step 15).
  13. Replace PCM. After replacing PCM, go to step 15).
  14. Replace electrical filter. After replacing filter, go to next step.
  15. Using scan tool, select DTC, CLEAR INFO. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC P0370. Operate vehicle within the conditions for setting this DTC. If scan tool indicates that this test ran and passed, go to next step. If scan tool does not indicate that this test ran and passed, repeat step 2).
  16. Using scan tool, select CAPTURE INFO, REVIEW INFO. If any undiagnosed DTC(s) are displayed, go to applicable DTC test.
RENDER: 1.0x

NO RELATED

Recommended Tools & Savings

Use the Manual With the Right Hardware

Pair factory procedures with proven DIY tools so the instructions are easier to execute.

Affiliate disclosure: We may earn a commission at no extra cost to you.

Shop Manual-Ready ToolsFree Quote CheckQuote Shield Pro

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.