2003 Dashboard, Horn, MFD Screen Problems P3002 & P1636

Time was, you'd buy directly from the Toyota materials distribution center, but like most of the manufacturers they've now contracted the distribution service to Helm, Inc.

-Chap

 

My post #2 above suggested several voltage measurements that you could take. If you can complete those measurements then we can comment on whether your mechanic buddy is correct with regard to the 12V battery being drained.

You are correct, there is no alternator in a Prius. Once the Prius is READY, the DC/DC converter provides power to the 12V bus including charging current to the 12V battery.

 

It would not hurt to try that test. First though, make sure that your 12V battery is fully-charged; if it is not, charge the battery first before doing anything else.

 

The 12V drain would not come from the transaxle since that is powered by high voltage 3-phase AC.

What is the quiescent current drain when the car is IG-OFF and all doors closed?

 

Measuring the quiescent current drain is quite simple: use a digital multimeter set to read current, and put that in series with the negative battery cable and body ground.

Understanding the quiescent current drain is really the first step in solving the problem. If you don't know what the drain is then you don't know how much of a problem you have.

 

[quote="slimfrancis, post: 1973417, member: 77943"
3. place one probe (lets say negative probe) to my negative battery terminal
4. place the other positive probe to body ground[/quote]

Yes - assuming you have first disconnected the negative cable that connects those two points. When measuring current in-line with an ammeter, you really do have to be in-line, forcing the current to go through the meter. If you're just putting the meter in parallel with the big fat wire that already connects the negative battery terminal to body ground, the lion's share of current will still be going through the wire where it won't show up on the meter.

As Patrick pointed out, once you have the meter in-line and the cable disconnected, the meter's current capacity is likely too low for the currents that would be seen if you turned the key on, so make sure you leave it off and measure only quiescent current that way.

I don't think for even a moment that you're on your way to replacing the inverter. Quiescent power drains in 12 volt car electrical systems have been problems for as long as there have been 12 volt car electrical systems. Your buddy has got you somehow thinking that it's a "complicated" hybrid car, so whatever's wrong with it must have to be in the complicated hybrid stuff. Once you see how much the quiescent drain is and when it occurs, you can just follow the wiring diagram to see where the various different circuits branch off that have power when the key is off, and move your meter to those one by one, and so on until you find the culprit. Only a few of the possibilities would even have anything to do with the complicated hybrid stuff.

-Chap

 

Most digital multimeters can measure current up to 10A. Use the highest current setting to start with, then move down to lower current settings as needed to get a good reading. Don't exceed the highest current that the meter is rated for, or else the meter fuse will blow. As Chap pointed out, leave the car IG-OFF and keep the cabin/trunk lights off. Keep the doors closed as much as possible because when the doors are open, the body ECU will draw more current.

I don't understand how your mechanic could do the work he did, without monitoring the quiescent current draw. Without keeping an eye on that measurement, you would have no idea whether the work you are doing is making the situation better or worse.

If you are going to do this work yourself, you need a long extension wire so that you can position the meter by the fuse boxes, allowing you to immediately see what happens as you pull fuses, one at a time. Make sure you insert a pulled fuse back into the correct slot.

When you find a fuse that produces a big drop in quiescent current draw, then you will need to refer to the wiring diagram. Look at the circuit downstream from that fuse to see what obtains power from that fuse. Then disconnect one circuit at a time until you find the component that is the power drain.

If you see a relay or two that is downstream from that fuse, try pulling the relays first as a stuck relay is the most likely cause.

This is not rocket science, but the task requires patience and the ability to think logically. If you visit your dealer to ask for this, expect to pay for at least four labor hours of troubleshooting time. Is it worth it to you to try to figure this out yourself to save $500?

My post #17 suggested you try looking at the circuits downstream from the 15A DOME fuse. Again, I repeat this suggestion to you now.