advice sought about 2002 86K with flashing fuel indicator, combometer ECU replacement?

I briefly saw this last week with our 2003 Prius. I went to start but did not turn it all the way to START and the key 'felt funny'. The fuel indicator bar would flash ON and OFF. I had not turned it far enough to engage START but some kind of a partial ING setting. So I turned the key OFF and tried again. It started normally and everything worked.

For me, an intermittent, and this incident last week was the first. But I was going to work and forgot to check for any codes. I'll check the car today and see if I can find anything.

Just a thought, you might call:
Auto Careers Development Center - Hybrid and Electric Vehicle Repair Training

I've got to run to work but I'll check the wiring diagram this evening. If I remember correctly, there are several independent circuits activated by the switch, not just single contacts for each group. I'm thinking 'crap in the gap' might have led to an unexpected power-up sequence.

Does the car otherwise drive normally? Just the flashing fuel bar?

Bob Wilson

 

Honestly, this sounds like it could be a symptom of a weak 12V battery. I would start there. Dealers have been notoriously neglectful in identifying weak 12v batteries in the Prius.

 

I highly recommend preemptive replacement of the 12V battery. As I stated b4, dealers are notoriously bad for being able to diagnose a weak 12V battery on a Prius. If your going to ask the same dealer that you've been working with, chances are, their pride will not let them tell you your 12v is bad (because they should have checked that first and it would be too embarassing to admit that now).

If your 12v battery is the original, go ahead and replace it now. I would give that a 90% chance of fixing the problem at this point. Even if it doesn't fix it, you really need to replace it anyway.

 

You might want to update your city and state. It helps us to identify specific resources that may be near your location.

Bob Wilson

 

I can name a few folks off the top of my head who should have been invited: hobbit and Patrick Wong come to mind including some of our local advisors.

Bob Wilson

 

The dealer saying they saw the flashing fuel bar after the battery change is probably just pure pride. Mechanics are prideful people and very unwilling to admit when they make a mistake. The sad thing about it is most people can't or don't hold them accountable for their mistakes. This allows them to "make up stories" to the average customer when they make a mistake. Most customers will not be comfortable with their own knowledge to challenge them.

I'm betting that your fuel bar is fixed and the 12V battery is what fixed it. I have seen this b4 on my Gen I when I had a weak 12V battery. If my diagnosis is wrong then, I will be the first to admit I made a mistake. I'm telling you that I will lose no sleep tonight wondering if I'm wrong (because I am confident that was your problem). I would not have the dealer replace the combo meter (especially at your cost) unless the problem returns (and I believe it will not).

 

Interesting!

I saw it once over a week ago when I didn't start the car correctly. I'll look over the electrical diagram and see if there may be some way to replicate the problem. Questions:

• Toyota has used their Techstream scanner and found no code?
• Your speedometer and trip meter appear to be OK?
• No other issues?

Thanks,
Bob Wilson

 

Guys,

Not sure if you've looked but I haven't seen anybody mention this yet - the fuel gauge flash codes are on page DI-661-1 (in my 2001 manual, maybe the pagination is slightly different for 2002). They are about five different codes depending on whether all the segments flash or just one, whether the pattern is a steady flash or groups of two flashes, and whether or not the letter E also flashes together with the bars.

I see the OP mentioned groups of two flashes. Is that with or without the E? Maybe if we start with what the meter is telling us, it will help decide what to do next.

-Chap

 

That's awesome info Chap. Learn something new every day.

 

Ok, so that makes it the inclinometer. There are actually two inclinometers, for the pitch and roll axes, and they are separate components mounted with screws near the combo meter and attached to it by short wires that plug in - you can see them here. They'd be easy to replace if you knew of a source for replacements. (I haven't checked whether Toyota sells them a la carte.) If that worked, it would save hassle with the odometer.

Of course it's hard to know whether the problem being signalled is in those inclinometer gizmos themselves or in some related driver component on the circuit board itself. But at least we know when the dealer said "inclinometer", they were looking up the code in the same book I am.

-Chap

 

Thinking more on this, I seem to remember that the inclinometer calibration procedure shown in the manual involves a mode where the inclination readings are shown (using the normal odometer digits) and are sensitive enough to show change if you shift enough weight around in the car. This is from memory because it's raining out and I'm too comfortable to go look in the manual again. But using that procedure you might be able to confirm that one of the readings is funky, and maybe even which one.

Maybe I'm wrong about them being sensitive enough to read shifts of weight in the car, but you should certainly be able to exercise the full sensing range by taking the mounting screws out and simply tipping the sensor left/right or fore/aft by hand. That should allow you easily to see if it's one of them or both that's out of whack. If it's one, you could (turn the key off and) swap the two sensor plugs at the meter board. You can't leave it that way because the two sensors have different mounting brackets to match the two axes. But as long as they're loose in your hand, swapping them and comparing readings could tell you whether the problem is with one of the actual sensors (funky reading goes to other axis when plugs swapped) or in the circuitry on the board itself (funky reading stays on same axis).

-Chap