Victim: 2007 Yukon SLT, 5.3
Symptom(s): Argumentative Owner; No Crank
Initial request: "Put a starter in it...just wouldn't crank one morning" [explicit(s) omitted]

Vital Statistics:
Active DTCs: 0 witnessed.
*Batt voltage(BV)? Nonexistant - Charge battery, remain on 12.3-12.7v trickle for duration of all conditions below.
*Bv+ Battery cable @ Starter? True
*Bv+ @ Start contact during crank? False
*Start relay condition? Tested, Passed, swapped with known good for testing.
*Start Relay to starter circuit? Applied jumper between pin (87) and (30) @ relay base; starter engaged, cranks, no start.
*Relay control voltage(pin numbers listed from here beyond are listed for reference, however possibly indicated backwards) at relay base? (85) BV+ during run and crank with or without relay load, 0+v when run/crank relay disconnected or key in off postion. (86) -5.4v to pin 85 at rest with no relay load 0-v with relay load, -8.2v during crank with no relay load 0-v with relay load.
*BCM input start command active during request? True, Inactive when key in run or off
*BCM input key in run condition active? True, Inactive when key off
*PCM start output command active during crank? True, inactive in key run of off
*Incorrect key attempts?: 0 indicated, system indicates functioning correctly, with conditions consistent with normal operation.

Notes:

**Negligible voltage drops between B- post and any grounding points and wiring tested**

**Negligible resistance between PCM connector and start relay pin (86).**

*Any other issues, related or unrelated? Rear hatch indicates open at all times, Remote start unavailable when hatch DOES indicate hatch open. Customer states "water got into radio years ago, I wonder if it triggered a theft protect".



Suspicion: PCM failed starter output.

Customer decision: Borrow a known good ignition switch from a buddy, Please install.

Anyone want to shed some light here? Suspicion based heavily on the pin 85/86 voltage conditions when compared to active commands.