P07C8: Intermediate speed B high can also report implausible pulse encoding

P07C8 is the high-circuit code for intermediate shaft speed sensor B, mapped here to the even-clutch speed channel. Its GM row includes more than one route to a fault, so the short label should not be reduced to one high-voltage measurement.

A stopped-signal branch differs from a running signal

The general average-voltage boundary is above 4.230 volts. A separate no-pulse branch uses zero sensor frequency together with average voltage above 2.640 volts. Other branches evaluate pulse-width validity and excessive changes in pulse width.

The sensor’s VSS2 supply must be above 8.25 and below 10 volts, with a separately valid battery supply. The row lists at least 300 milliseconds of confirmation, excludes cranking and STOP state, and is disabled by P0882/P0883.

Determine which representation is questionable

Preserve frequency, average electrical level and pulse information rather than relying solely on the calculated shaft-speed PID. A high electrical level at zero frequency is different evidence from malformed pulses while the shaft signal is active.

The non-direction-pulse clause has unclear logic between incompatible printed width bounds and is left unresolved here. No corrected specification is invented. Use the verified branches to understand the fault context, then consult the exact transmission procedure for waveform testing and channel mapping. The code alone does not identify the sensor, harness or input electronics as the failed part.

Source and applicability

This explanation covers the cited GM monitor, not every vehicle carrying this code. The application-matrix filename does not resolve cleanly to this file, so no model or engine fitment is assigned. GM diagnostic table, PDF page 919.