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Home >> GMC >> 1991 >> Value Van 7.4 N >> Repair and Diagnosis >> External Pages >> Different car >> Section 147 (Cruise Control System) >> Self-Diagnostic System >> Entering On-Board Diagnostics >> DRB Diagnostic Mode

DRB Diagnostic Mode

WARNING: This page is about a different car, the 1995 Dodge Pickup and 1995 Dodge Cab & Chassis. However, it is still accessible from the selected car via links, so may be relevant.
  1. Turn ignition off. Connect DRB to data link connector. Data link connector is located in engine compartment, near PCM.
  2. Start engine (if possible). With foot on brake, move transmission shift lever through all positions, ending in Park (A/T). Turn A/C switch on and then off (if equipped).
  3. Turn engine off. Without starting engine again, turn ignition on. Enter selection No. 1, STANDALONE DRB. Enter selection No. 1, CHRYSLER DOMESTIC. Enter selection No. 1, ENGINE. Proceed until READ DTCS selection is offered. After trouble codes are accessed, see appropriate TEST SC-1A  (CHECKING SPEED CONTROL OPERATION) to diagnose problem.
  4. To erase trouble codes while in this mode, press BACK key. At DRB display, scroll to YES - ERASE FAULTS. A confirmation message should then appear, FAULTS ERASED.
NOTE: Not all trouble codes apply to all vehicles. Some trouble codes have more than one meaning. When a trouble code has more than one meaning, MIL is unable to distinguish between different failures.
DIAGNOSTIC TROUBLE CODE (DTC)

Code  Display On DRB  Fault Condition 
11 (Diesel Only) NO CRANK REFERENCE SIGNAL No Crank Reference Signal At PCM Detected During Engine Cranking
15 NO VEHICLE SPEED SIGNAL No Vehicle Distance (Speed) Sensor Signal Detected During Road Load Conditions
34 SPEED CONTROL SOLENOID CIRCUITS An Open Or Shorted Condition Detected In Speed Control Vacuum Or Vent Solenoid Circuits
34 SPEED CONTROL SWITCH ALWAYS LOW Speed Control Switch Input Below Minimum Acceptable Voltage
34 SPEED CONTROL SWITCH ALWAYS HIGH Speed Control Switch Input Above Maximum Acceptable Voltage
55 N/A Completion Of Fault Code Display On CHECK ENGINE Light