My 97 Yukon, 2wd won't start. Something failed after I turned the ignition
key, heard the engine starter and engine turn, then stop abrubtly. The
next turn of the key resulted in a single click that was traced down to
come from the "Remote Activation Control Module" underneath the dash near
the steering colomn. After this click, with the key turned completely
forward, the key does not even attempt to start the engine, instead
silence. The battery is fully charged, but something is preventing the
connection through whatever soleniod may exists down there. Additional
info, the door locks do not work either, when the door "unlock" is pressed
and held in, the clicking sound is repetitive until the button is release;
furthermore, intermittent power to the radio. What do you think is causing
this "short?" or whatever from me being able to start my 1997 Yukon?
Answer: This Yukon is installed with a Pioneer DEH977DH oversized radio.
Some of the optional features for this radio allow for security.
Specifically, the radio taps into the car using Single Pole double throw
(SPDT relays). For example, a SPDT relay is used to levarage the car's own
car horn when the alarm has been activated, it closes the circuit. The
radio connects to yellow ignition wire with a SPDT relay to help prevent
theft. This is the ignition shutoff feature. Well, what happened to me was
that the quick key turn somehow activated the ignition shutoff, and fried
the SPDT relay. This cause the weird electrical problem, (maybe it fried
my battery, or maybe the battery caused this, but I had to replace my
battery, bad cell). To fix: 1 brand new battery $80, 1 new SPDT Relay
$4.25 at Autozone.