Rick Raldiris

I recently discovered the problem for my mystery loss of functions on my 2004 Silverado SS, which made no sense. I too had a driver’ power seat that suddenly did not work with all fuses, relays & connections good. Later my mechanic could not power up the windows after disconnecting the battery to replace a power steering pump. My problem came from a Python alarm system with a battery back up. Originally, I had a Code Alarm installed in 2004. This CA alarm had a feature for a back up battery in case the thief drilled thru the fender to kill the battery. The CA had a separate input for the back up battery, which isolated it from my main battery. By 18 years later, the CA alarm & replacement Audiovox alarms no longer worked & were obsolete. My latest installer simply connected the “back up” battery in parallel with my truck’s battery, which was NOT a separate input circuit. So whenever, I replace a battery or disconnect the battery to replace components (like remove air bag to replace a steering wheel), this back up battery maintained a voltage for a long time. I just happened to discover this, as I had a cigarette lighter volt meter inserted. 1/2 hour AFTER I disconnected the battery, I saw 8V on the read out. The bottom line is this present, but degraded voltage is causing the truck’s PCM computer to loose its mind. I am certain of this, as this occurred 3 times to me, losing different functions (lost all gauges, or lost interior lights, etc; but truck would start with headlights functioning). I need to get alarm guy to either remove this BA battery or install a relay to isolate this BA battery UNLESS the truck is running OR alarm is triggered. This also explains why my Optima Yellow top battery kept discharging when the truck sat parked for 6or more days. I measured 4/10ths Amp before having my LoJack ripped out, but I still read 1/10th Amp drain using my Fluke DVM with DC Hall effect clamp on transducer. These residual voltages REALLY confuse the vehicle computers on this age.