Low Voltage in Rear Power Outlet

If it was me, I'd get one of these:

Get an extension cord for it if you can't find someone to watch it while you drive. See what it does with no other load. Gather data like that with and without a load and then go see the dealer. It should be under warranty.

Or it may be that the wire feeding it is not big enough to power a 60W load plus the overhead of the inverter itself, which would pull down the voltage, but ought to blow the fuse. Does the manual give a maximum load for the outlet?

 

Yeah, if it worked in the PiP, it should work in the Prime. I'd head back to the dealer. Might be a poor connection in the wiring causing a voltage drop, and that's a potential fire hazard.

 

A loose connection or bad solder joint could do that as well. Dealer should fix it for free.

 

If you move your voltmeter to various other spots in the car's electrical system, do you find other spots where shifting to D makes it drop by a volt? That puzzles me.

-Chap

 

does it happen on the front outlet as well?

 

agreed. free loaner?

 

Anybody else's Prime reduce the DC/DC converter output by a volt when shifted into Drive? I wonder if that could be by design. I don't have a ready guess as to why that would be a useful design, but it sounds very deterministic, from the description. Perhaps to charge the aux battery at a higher rate when just sitting around, preserve more power for other purposes when driving.

Anything about it in the Prime New Car Features manual?

-Chap

 

I have a scanguageII connected with volts as one of my options when car is in ready or drive the voltage is 14.2 volts, when I turn the car off the voltage drops to 12.3 volts, the next morning the battery voltage is at 11.9 volts before I put car in ready mode. It always jumps to 14.2 volts when I put the car in Ready mode or drive mode.

 

you need a new 12v my friend

 

Only if I do too, and on my list of things to worry about that's nowhere near the top.

Rather like the voltage readout on the MFD, the voltage readout on a ScanGauge II is actually what's measured by the ScanGauge itself on the always-hot pin 16 of the diagnostic connector. That's downstream of the battery by several small voltage drops, and if I saw those numbers on mine, any thoughts of imminent battery shopping would be far from my mind.

-Chap

Edit: as an exercise, walked right out to my car just now, opened driver door, waited for brake pump to finish, pushed button on ScanGauge, read 11.9 on the nose. Not having any battery-related difficulties and not expecting any. Maybe I'll be wrong....

 

There’s a general explanation of the charging system, as summarized in a previous thread, but nothing quantitative, other than the basic specifications for the auxiliary battery. If the auxiliary battery failed the load test, it should be replaced, of course, but I wonder if the battery state sensor assembly might also be faulty, which could lead to improper control of the DC-DC converter output.

If I were diagnosing the problem, after replacing the battery, I’d do the complete procedure in the Repair Manual (more info) under Power Source/Network: 2ZR-FXE Battery/Charging: Charging System: On-Vehicle Inspection. I’d also compare the current and voltage measurements during the last steps of that procedure, and a thermometer measurement at the sensor assembly, with the values for Auxiliary Battery Current, Auxiliary Battery Voltage, and Smoothed Value of Auxiliary Battery Temperature, respectively, shown in a Toyota Techstream diagnostic system connected to the car under Powertrain > Hybrid Control > Data List, just to verify that the data reaching the hybrid vehicle control ECU from the sensor assembly are reasonable.

Sensor faults are supposed to be detected automatically, but the detection limits for the associated diagnostic trouble code (DTC), P058A01, Auxiliary Battery Monitor Module Range/Performance, as listed in the Repair Manual, are fairly loose, and I can imagine that a sensor reading could be wrong enough to cause odd behavior but not far enough out of range to cause the DTC to be stored.

 

Yes—though the constant voltage should be closer to 14 V than 12 V, I’d expect—but only if the failure is one that the hybrid vehicle control ECU has been programmed to detect, or if at least one of the other programmed conditions for constant voltage control mode is satisfied.

Perhaps; that’s the kind of insidious failure I meant to suggest above.