Help! Parking lights NOT working, all other lights working

Did u also check the fuses that are under the dash

 

Here's the circuit: The light control on the stalk sends voltage to the Body ECU, which then turns on the relay T-LP. It is located in the driver side junction block, under the dash ( a bit of work to get to it. Here is a look: http://techno-fandom.org/~hobbit/cars/bodyecu/ .) That relay then sends voltage to all the tail lights, via the 10A tail light fuse. It also illuminates the dash panel lights, via a second 7.5A panel fuse. If you can turn on the light switch on the stalk, and the panel lights come on, then you know the switch and relay are OK. If not, then the relay, switch, or Body ECU is suspect.

You should be able to listen close to the Body ECU, reach up to turn the light switch, and verify that there is a relay click.

The same tail light circuit also turns on the license plate lights and the glove box light. If those are not working either, then I would suspect the 10A tail fuse. At that point you would have to take your meter and check for voltages and look for wire harness rubs that may be causing a short condition. It is possible one of the tail lights developed a short, which would take all the others out. The ground points are not in common for all those lights, so a loose ground connection is not indicated.

 

OK, it was late last night. With less blurry eyes..... If the license plate lights are good, then it should be the ground point for the tail lights that is corroded. It is under the hatch back, in the middle. You will have to take the plastic insert out of the back area to get to it. Let us know what you find.

 

nh70 has pretty well gone through the system. The only snag I see is that all the lights within the rear cluster use the same ground point including the stop lights and indicators, and you say these are working. I assume you have checked that the bulbs are ok as it would not be the first time on this forum that more than one bulb has been found to have failed.

 

Don't forget to check the bulbs, just in case. I have seen at least 2 out at the same time.

 

Toyota made a rather poor choice in using this type bulb. If this is the first time you needed to replace the bulbs then you got perhaps 2 to 3 times the average life out of them.

 

No, it would make them dim or not work, but wouldn't cause burn out. Check your 12V system voltage. Excess 12V can cause early bulb expiration. As one bulb goes, the voltage across the other bulbs increases a little, and that accelerates the situation. But hey, these things happen. Maybe a chance for replacement with something better.

 

Those little bulbs don't last a long time. I have already changed two of them in the two years time that we have had our Prius (09 model) that we bought used. It is a good idea to check your lights at least once a month. Try to get into a habit of checking the lights when you check your air pressures on your tires. Keep a set of bulbs in the glove box, so when you see one out, simply change it and go on down the road.

Hope this info help you.

Ron

 

I have read in other posts that when one bulb burns out, that the voltage applied to the other bulbs is a little higher. If you see all four go out again in the next few months, then you probably need to check the voltage at the light bulb socket. I am willing to bet that the bulbs had simply expired. They have very small filaments in them.

Ron

 

I have a theory as to why the tail lights blow but not the number plate lights.

Each tail light shares the same ground wire as all the other lights within the light unit, so when the indicators (turn signals) are operating at the same time as the side lights are on, the voltage drop in the ground wire will increase dropping the voltage to the side lights when the indicators are lit and raising the voltage as they go out.

This will give a 1HZ square wave voltage pulse to the side light on the same side as the working indicator. I have not measured the cold resistance of the indicator bulbs but I suspect the cold filament current could be as high as 5 amps although running current would be slightly less than 2 amps.

The same applies to the front side lights.

 

I have the similar problem, no panel lights or front running lights..new front bulbs, fuse is good, dimmer switch is all the way up where it clicks,tail lights and plate lights work...just the front and panel lights are out, is there a common ground for the front section? thanks

 

Driving a 2009 Prius we've had since 2014.

We just encountered the faulty marker/parking light problem. Simplest solution solves the problem.

2009 Prius had been sitting for 2 1/2 months - following the running battery replacement in January. It had been driven for about a month prior to being put into storage. Always had a problem with left rear taillight going out - after frequent replacement.

Had not been driving it at night until this 4 July. NONE of the marker/parking lights would light! Had to drive from Stockton to Fremont with flashers on!! Next day check everything - fuses, relays and finally- bulbs. Two of four bulbs found to have busted filament: two bulbs were LOOSE in teh socket. All new bulbs installed and a slight slathering of DIELECTRIC GREASE to assure conductivity. Also fiddled with teh connection at left rear to tighten the clip.

Simplest solution solves the problem.

 

You do realize the word 'dielectric' means 'insulating', right?

 

That it does. But when used on electrical contacts, it does not remain between the points of metal-to-metal contact, it ends up around those points, protecting them from environmental influences, but not increasing the contact resistance by any meaningful amount.

I say this as someone who used to be one of the people saying "you know that's an insulating grease?" myself. But enough people did me the favor of confronting me with actual evidence that I eventually even did a direct experiment myself, and reality compelled me to change my tune.

'Dielectric' still does mean something that doesn't conduct. And it's still true that any significant layer thickness of dielectric grease will be a nonconductive layer. Only that isn't the end of the story when the grease is used in an electrical connector. And that has been known to electrical connector designers for years and years; the one doing the late catching-up was me.