Instrument Panel Problem (with video!!!)

[toi]

I did try to figure this problem out by using search here and i did indeed found similar topics with same experience but noone seems to know what really causes the problem.

This car is a 2006 prius at 182,xxx miles on the clock with stock everything,original transmission and engine.Only routine maintanence done so far.It is used as a cab 24/7.It has a toplight and a taxi meter installed (of course)

Here are my symptoms with the video.

When i start the car,the instrument panel (speedometer,gear panel,fuel gauge) does not light up.

Putting the car in reverse , the backup lights wont turn on and the back up camera wont work.

It has a taxi meter and it gets signals from the transmission,it does not charge the right amount for the distance.A ride that costs around $28 would only be around $10 when this problem occurs.

The instrument panel lights and all the rest comes back on and operates normally as they please.So i can not tell if there is anything wrong specifically somewhere .The mechanic checked all the fuses and found nothing.I checked every possible connectors around the body where i can reach for something loose but everything seems to be good.

Posting the video through this link on youtube , hopefully someone could spot the problem and give me and others an advice who are having this problem.Got my fingers crossed.

YouTube - Picture 040

YouTube - Picture 040

[EZW1]

Does everything come back on when sitting still or while driving? I suspect a loose connection somewhere. These can be a bugger to diagnose. Probably the easiest way for you or your mechanic is, when the problem returns, start wiggling every connector while checking the display. You'll know when you find it.

[toi]

It'll be working when the car is on and then when you turn it off and turn it back on.This problem happens out of the blue.It doesnt do this while driving.I mean when the dashboard lights are on when you start the car ,the lights will stay on till you turn the car off.Very very weird problem.I checked every possible connector so far and no luck.

[Patrick Wong]

Originally Posted by toi

...I checked every possible connector so far and no luck.

Intermittent problems can be really tough to fix. Unfortunately your car has become an example of how a high-mileage Prius may be difficult to keep running, due to an electrical problem.

When you say you checked every possible connector, does this include removing the instrument panel plastic trim (which includes the passenger-side airbag) so that you can access the combination meter (speedometer, odometer, fuel gauge, warning light assembly)? I suggest that if this has not been done yet, your mechanic will need to gain access to it. Then remove the meter and inspect the wiring connector and the mating socket. Clean if necessary with the correct spray solvent for electronic switch parts, then reassemble. Maybe that will help, maybe not.

The combination meter receives 12V power from three fuses: 10A GAUGE, 15A DOME, and 7.5A IGN. Check those fuses again to see if they are secure in their sockets and if there's any problem with the wiring. When you experience the problem, use a digital voltmeter to measure the voltage on both sides of those three fuses: if you don't measure voltage on one side of a fuse, that is evidence that the fuse is bad.

The backup lights are controlled by the combination meter, more evidence that part is the source of your problem.

Has the vehicle suffered any accident damage that would be relevant to this problem?

It might also help to disconnect the taxi meter while working on the problem, to make sure that device is not a contributor to the problem.

Good luck.

[lusciousgarage]

Luscious Garage | Hybrid Specialists | LG TV - Prius Dead Dashboard

[HTMLSpinnr]

Side note - cycling the HIDs like that is a sure way to shorten bulb life substantially.

[Patrick Wong]

Originally Posted by lusciousgarage

Luscious Garage | Hybrid Specialists | LG TV - Prius Dead Dashboard

Hi Carolyn,

Thanks for providing the link to your informative article. One question and one comment:

1. Any sign of coffee or other liquid stains on the failed combination meters that were removed?

2. Thanks for pointing out that the failure of the car to power down is due to confusion about whether it is at speed or not, and that holding down the POWER button is a way to force the power down. Otherwise, I was thinking it would be necessary to disconnect the negative terminal of the 12V battery, then remove the traction battery's orange service interlock.

[lusciousgarage]

Hi Patrick,

1. The first cab had some powdery substance on the back of the control board and we thought "a ha!" The next one was visually perfect. Go figure.

2. Again at our first brush with this issue, it took a while to get the car to act up consistently. When it did come in BROKE the power button also didn't work. First step was hooking up the scan tool and looking for CAN confirmation of power button inputs (or lack thereof). Datastream showed button inputs just fine (it also showed open requests at the hatch button). So why denying it? I was already back probing powers and grounds at the cluster, and when I finally disconnected it entirely the button worked normally. Then the question was, "what does the cluster offer to override the power button inputs?" The assumption was speed.

This is not uncommon with contemporary (i.e. computer controlled) cars, actually. A common case is when the speedo doesn't work and you hook up the scan tool and look to see if you can see vehicle speed at the engine ECU. If speed shows then you suspect an internal fault with the cluster.

When the car acted normally with the combo meter disconnected, obviously the cluster needed to go. It was pulling down the communication bus, affecting the power inputs and the hatch, etc. I spent some time studying the wiring diagram, which ultimately illuminated the BEAN gateway aspect of the speed information to the Power ECU and Body ECU. The combo meter gets speed info from the Skid ECU (wheel speed sensors) over the CAN bus, which means that everything else on the CAN bus gets that info too. The Power ECU is on the CAN bus too (Body is probably also, but I don't remember and the diagram isn't in front of me), but it clearly listens to speed from the BEAN network, not CAN. Interesting car to be sure.

Very best,
c

[toi]

thanx for all the replies.it was the combination meter indeed,

got one off ebay with 16,000 miles on it for $170 shipped and put it in.solved all these problems at one shot.since it is a cab i didnt care about the mileage difference.

[Patrick Wong]

Thanks to Carolyn for providing the theoretical explanation for why a combination meter failure can cause the problem; and thanks to toi for confirming this was the problem behind the OP.