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Yea, that's the one. If the parasitic draw is still there after pulling the R7 MGC relay, wouldn't that mean the draw is not caused by the a malfunctioning MGC relay?
Most likely. However, a malfunctioning relay could pose a danger to downstream components, including the AC amp. So, you need to test all components that could potentially screw up parts like the AC amp if you decide to replace it.
Originally Posted by cyclet
My understanding is that a relay is like a big fuse designed for high-amp loads with additional functionality of being able to act as an on/off switch for a circuit. I could be wrong though, definitely not an electrical expert haha.
Partially true, but, the relay does not act as a fuse. It is essentially a switch that can use a low-amp control signal (from an ECU for instance) to switch on/off a high-amp load (like the mag clutch, for instance).
Thanks to nevernu, you now have the information needed to troubleshoot several of the circuits and components in the AC system. You may need further assistance with the other components connected to the AC amp, to ensure that you won't blow up a new amp, if needed. I would recommend you test your AC clutch, fans, compressor, pressure switches, and any other components in the system. They all have test procedures in the shop manual. Don't assume that replacing a blown amp will fix the problem, as any one of the components or their associated relays that may have ruined your old amp, could do the same to a new one.
Unfortunately, your electrical problem is not uncommon, and electrical problems in general are sticky-wickets. That's why they are so expensive to have fix professionally. Oftentimes the pros face the same challenges as we, the DIY people face, and sometimes they jump to the wrong conclusions and end up costing the car owner for their mistakes! So, take your time, and think things through before throwing parts at it. Otherwise, consider taking it to a specialist AC shop with good Yelp reviews. They've seen every kind of car, and every kind failure, so their experience is invaluable in getting your vehicle back to normal.
Update. If I read the wiring diagrams correct, everything that is downstream of the A/C CTRL PNL fuse should be in the glovebox cluster of electronics. I've gone ahead and disconnected not just the A/C amplifier but every single other ECM, ECU, TPSM, power mirrors, body controller, and all other modules that are located in the glovebox region. Even after all that, the 100mA draw is still there.
Even though I know it's too high, I'm starting to think 100mA is just the normal parasitic draw for an 2007 ES350? Can someone with a properly functioning 2007 confirm or deny this theory?
07-09-22, 12:43 PM
