Test H: DTC 34

Diagnosis H: DTC 34 Set (Wiring Diagram):

Diagnosis H: DTC 34 Set:

OPERATION:
Circuitry In the DERM develops and stores electrical energy at about 36 volts. This energy supply is called the 36 Volt Loop Reserve Power Supply (36 VLR). It acts as a backup to the battery to help make sure the SIR system can operate when the vehicles's electrical system Is damaged. The DERM can monitor 36 VLR voltage internally and at the sense low terminal A6. By comparing the 36 VLR voltage with preset limits, the DERM can spot problems.

POSSIBLE CAUSES:
DTC 34 - Sets when sense low voltage is low for the first half second after ignition switch is turned to RUN. Sense low is pulled up by both ignition and 36 VLR. It normally reads battery voltage as the ignition switch is turned to RUN, then it reads a higher voltage as 36 VLR charges. The brief "look" at battery voltage tells the DERM that the ignition supply to the DERM Is OK. Note that DTC 24 often sets along with DTC 34. DTC 24 is set by low voltage at sense low also, but without the time factor. DTC 24 can set anytime while DTC 34 can set only during first half second.