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Toyota Prius Electrical and Lighting Questions

boraboraborabora Posts: 16
i have a 2007 prius, after my trip outside town for 2 weeks, the 12v battery went dead. this has happened twice. The dealer said that it is usual. the only solution is to unplug the battery before and it will take about 1/2 hrs to do so.

is that right?


  • birgerbirger Posts: 80

    We're very near to deciding on getting a Prius. In Europe, the vehicle does not have HID headlights, not even as an option. Having had a positive experience retrofitting OEM HID headlights to a Mercedes ML, I would like to know if any US owners have been down that road, and if they could share their experiences.

    On the ML, with the help of a couple of "pigtail adapters" ist was a plug&play operation, and the result was absolutely stunning.

    TIA for your feedback.

  • Just passing along some info about headlight (bulbs)...I recently noticed a driver's side headlight out on my 3 yr old '04 Prius. When I went to purchase a replacement (BULB) I had several selections to pick from (cost ranging from $8.00- $22.00). I selected a lower priced bulb and went home to my garage and attempted to change the bulb myself(as I had done so many times B/4 in many of my other past cars). Unfortunitly what a task I had B/4 me. Upon opening the hood I realized the opening behind the headlite assembly is next to impossible. I removed the cover to a module just behind the headlite and tried again to get to the bulb unsuccessfully. Then I called "TOYOTA" for help at the dealership. They explained I had to turn a rubber cover & pull out that cover and release a wire clip and then turn bulb to remove. I tried and tried to no avail and finally took it to the dealer who(thank God) let a mechanic show me how it's done. It still took 15-20 minutes to get it done. While he did the miracle job he pointed out that some of the "Celica" modules are even harder to replace requiring that the bumper has to be dismounted to replace a bulb. I guess I'm lucky by comparison. Anyway...Thats that! Live & Learn. I hope no one has to deal with a bad bulb. As for Toyota...Does it have to be so darn hard to do what use to be a snap.
  • ck90211ck90211 Posts: 149
    I tried to install a HID kit (light, ballast, transformer, etc.) into a 2007 Prius, and for some reason could not get it to work. That's after testing all electrical connections with a voltmeter and things. So I for one would raise a white flag on such project. The standard lights are not too bad, so you won't gain much visibility using HID, especially if you get the hot (blue or purple) ones.
  • There is more to it than just the headlight [non-permissible content removed]'y. My '07 pkg #6 has 'em. There is a level sensor on the rear axle. when the car is loaded down the front end rises. This may blind oncoming drivers if not compensated. Also, the quality of the reflector and lens can make a significant difference in the performance. "Non-factory" systems may not do anything more than throw a bright light - not a "true" HID system.
  • birgerbirger Posts: 80
    Hi again,

    and thanks to the people who have answered the original post. Meanwhile our new Prius:


    has been ordered, and will be here in a couple of weeks :)

    However, it seems to me that some of you have not really understood what our intentions regarding HID were. What we were thinking of was - like we did on a 2000 Mercedes ML - to purchase the complete ORIGINAL Toyota HID headlight units and replace the ones on the vehicle.

    On the Mercedes this worked out perfectly, even without the auto leveling sensor - we drove that vehicle for some 6 years without getting flashed by oncoming drivers.

    The question was whether this would pose problems connection- or software-wise - not whether one of the various, very dubious aftermarket HID bulb adaptions would be possible.

    As the delivery date is now getting very close, we'll probably for the time being make do with a set of optimized H4 headlight bulbs from a recognized manufacturer - but it would be nice to know if anyone had done the OEM swap.

  • PF_FlyerPF_Flyer Pennsylvania Furnace, PAPosts: 7,965
    Since we don't have a discussion for Prius electrical/lighting issues, I'll rename this one to use as the starting point.

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  • pathstar1pathstar1 Posts: 1,015
    The HID systems draw about 1/2 the power of the halogens, so I wouldn't expect any power problems swapping in the stock HID system. You do need the level sensor to be legal (though you'd have to check on this in your country). With the stock system, I don't think it would be easy to operate it without the level sensor. It would be expensive to purchase all those parts. Perhaps finding a wreck and getting the parts off it would help. I'd estimate $2500 for each side for the headlamp assys. and ballasts. Wires would have to be added - Toyota doesn't make just one wiring harness for all the Prius. There may be software issues on the CAN bus, as I believe the HID control/ballast units "talk" to the rest of the car. So you'd need either a good Toyota tech. to do it for you or the tech manual including schematics to do it yourself.
  • birgerbirger Posts: 80

    Seeing that retrofitting OEM HID's to our new Prius will not only be quite expensive, but could also be downright impossible due to the electronics involved, we've decided on the second best solution:


    When we get it on Friday, a set of Philips X-treme Power H4 bulbs will be fitted - they're supposed to be 80% brighter than the stock H4 bulbs, yet still legal.

  • I had to jump my wife's 2007 Prius this morning. The car has about 400 miles on it, is 1 month old, and was driven yesterday. The car was completely dead. Unfortunately, I was not there when she turned the car off and exited yesterday. Nor was I there when she got to the car this morning. Here is what she reports:
    1. She parked, hit the P button and the Power button. She unplugged her iPod from the power adapter but left the adapter itself in the 12V outlet. (Simple adaptor with no apparant capacitors or power draw.)
    2. She exited the car, and pushed the exterior lock button on the door. Her key was not left in the car, so it could not have been left inadvertantly running all night.
    3. When she got to the car this morning, about 16 hours later, the car was unlocked. No interior lights came on. Nothing happened when she hit the power button. She was unable to start the car using the manual key.
    4. There was no visible damage to the car (other than below). Her iPod was still in the center console.
    5. Last week, she was hit on the driver's side by a guy turning left from a side street. We are still awaiting the insurance resolution to get the damage repaired.

    My only theories here are:
    1. Mechanical failure within electrical system: I haven't seen any other reports of this problem on Priuses, except when they have been left idle for a couple weeks.
    2. The Alarm was going off all night, unbeknownst to us.
    3. The damage to the door caused some short circuit which is draining the battery, perhaps by repeatedly locking and unlocking the door.

    Any ideas?
  • Hi,
    Happened to me last week. When I closed windows for the evening I'm sure I did not push the PWR button the last time to turn off the system.
    The "smartkey" outsmarted me. In our previous Prius we had to put fob in slot.
    BTW you can connect a battery charger to the spots. Mine was Ok in 15 minutes.
    Of course your damage may be the cause.
  • pathstar1pathstar1 Posts: 1,015
    It's possible an interior light was on. That will drain the 12V battery. This makes it impossible to start without "boosting" it. Perhaps the side damage caused the door switch to keep the light on?
  • stevegoldstevegold Posts: 185
    It happened to me once when my 2004 was new. I jumped the small battery from the special under hood connections and it has worked fine ever since. I did buy a small battery, enough to start the computer, made the cigarette lighter outlet "always on" so it would power the computer, but have never had to use it for that purpose.
  • anna_g87anna_g87 Posts: 1
    i am having a/c issues as well. mine is a 2/05 prius bought brand new. i love the car for the mileage i get but recently it will cost me $$ for repairs. i turn on the a/c, blower works but no cold air. i brought it in at a toyota dealership to get diagnosed and according to the tech they found a small hole in the condensor and the whole a/c unit, condensor and receiver dryer needs to be replaced at a cost of $1300 ... i bought additional warranty but they don't consider that to be covered. now it's an out of pocket expense ... but how did that HOLE get there? it took a while for them to diagnose the problem, they had to place a DYE in the system to see where fluid was leaking ... it's a really small hole according to the tech. i'd have to trust them on this since i have no clue about cars. but how can i get the warranty to cover this? ... it's only 2 years old. i've had 3 cars before the prius and i've never had to replace the a/c condensor unit in any of my previous cars.
  • Perhaps this is being seen to warrenty as "Road damage" in otherwords the problem is not due to the failure of a part. Perhaps a rock or other item flew up from the road and made this minute hole. Look at your warrenty, especially the small print and see if indeed it is excluded. If you don't trust them you could take it to a private air conditioning business that someone you know highly reccomends and get a diagnosses and see if thats what they find, true it will cost to diagnose but it is a thought. Quite honestly I don't believe they will find my problem because they take it apart put it back together and then it works...they can't fix it because they can't find a broken part to replace they have had it 3 times so far. They don't charge me however my car was purchased to go between California and Arizona and its not going to do me anygood when i'm in Arizona and its 112 outside. perhaps you can go to the official"Toyota Web site and inquire there from the corporation. If I get mine fixed I will post it. I will check to see if you post additionally also, good luck.
  • steve1csteve1c Posts: 3
    It recently cost me over $300 to take care of the 12V battery dying suddenly with no dashboard indications of impending doom. The cost was about $100 for the tow to the dealer, and $215 for the battery and labor. Not a warranty item (a 2004 Prius w/60K miles, although I do have an extended warranty to 100K miles and 5 years).

    We had just pulled into the parking lot of a local (Vegas) nursery, and the dash displays went stupid when I attempted to shut off the car. Nothing worked, and there was a bad/ strong (hydrogen sulphide like) smell in the car. Can't open the back hatch when the 12V system is dead, so it was difficult to get to the battery, buried in the back end. It was also hard to move the car onto the tow truck since the system has to be powered up to shift into neutral. We finally used the under-hood jump point to bring up the computers and switch into neutral. It took about 3-4 tries. The dealer confirmed the 12V battery had gone bad, and they replaced it. Everything works fine now. Just not happy about the cost, and I wonder what would have happened on the open (out in the desert) road or in traffic. :mad:

    Here are what I see as design deficiencies: 1) 12V battery location in the passenger compartment, with potential for noxious fume generation and lack of ventilation; 2) lack of a remote, mechanical release for the hatch; 3) difficulty in placing the car in neutral should the 12V battery be disabled, or at least, lack of driver manual guidance for this situation; and 4) little or no warning that the 12V battery was going south. (In most conventional cars, we all know the symptoms: slow cranking, especially when cold; lights dimming). Had Nothing on the dash by way of warning.

    Toyota Customer Service was pleasant, but basically read me the standard responses, and would not allow me to talk with technical/engineering personnel. Said they would pass my concerns along. Offered reimbursement (which I passed on) to "re-establish my lost confidence in the car." (I had expressed the concern about this happening on the open road or in Las Vegas traffic. Paying for the repair had nothing to do with them addressing the technical issues and my shaken sense of confidence.) I am really curious whether other owners have had the same thing happen...
  • pathstar1pathstar1 Posts: 1,015
    Your points are well taken, but I hope my clarifications are applicable.
    1. The 12V auxiliary battery is ventilated to the outside (hose connected to it). It is true if it bursts this would be bypassed, but that is not very likely. The battery is similar to a motorcycle battery in that it has a vent tube.
    2. Absolutely, a mechanical hatch release, even on the inside, would be nice (I thought I read it could be opened from the inside but perhaps not).
    3. The inability to put the car in neutral has been "complained of" before. One fellow had the car in a small garage when the battery died. Tow truck operator put the front wheels on dollies to get it out. He could have just connected a small battery to the under hood "boost" point.
    4. Maybe time to purchase a "Scangauge". It is an OBDII reader that will display up to four readouts in real time (all the time) out of about 18 choices. One is battery voltage. It sticks on the dash or wherever using velcro. Very handy. It can also read codes, reset codes, and act as a "trip meter". It can also be used in any vehicle 1996 or later (standard OBDII port).

    Looks like you got a good price on the battery anyway. Some owners were charged over $300 to have it replaced. As for the towing cost, a AAA membership saved me those costs for towing. Paid for a couple years membership.

    I'm surprised it failed so soon. Does the sun shine on the passenger side of your car when it's parked at home or work? Heat is very hard on lead-acid batteries.

    A few owners have purchased one of those portable "boost" devices. They are portable 12V batteries, and they double as 115VAC power providers, some even have tire pumps built in. Not too expensive (under $100), at Autozone or Pepboys, I think I read.
  • evgnatevgnat Posts: 1
    My 12V battery on 2004 Prius turned out to have a bad cell (as tested by the dealer service) and I had to replace it today. It is not readily available at the dealers and there was a few weeks wait at a few dealers to get it. It looks like Toyota has changed the battery model number at least twice in last few years.

    Looking back, I have had the battery die on me twice in last two years but I had blamed it on something not turned off. Now I think it was an early warning for a bad battery. Recently it died two times in two weeks and also gave a weak display some times while turning on, after which I took it to a dealer. Alas, I found out out that I had exceeded 3yr/30K warranty on the battery by two weeks.

    Word to the wise: get your battery checked out if it has died early in its life and unexpectedly on you.
  • steve1csteve1c Posts: 3
    Well, you won't convince the tow truck operator that the battery was vented outside, because he complained about the fumes inside being bad, as he struggled to find that latch release.

    We finally did find the mechanical release for the hatch. It is not obvious...even after looking at the manual. You have to put the rear seats down, remove the carpet and pan, pull open a small access on the hatch, and then feel around with your fingers for a small lever that will release the hatch.

    Thanks for the lead on the scanguage. I'll check it out.

    The car is normally garaged, except when I'm at work. Then it does sit in the desert sun. Still, I've had other cars out here that had batteries last 4-5 years no problem. And it never cost more than $60-70 to put in a new one myself.

    I would still like to hear if anyone has experienced or heard of a Prius going dead while it's in motion.
  • pathstar1pathstar1 Posts: 1,015
    You must have had a cell short on you. Sometimes a piece of lead comes loose and shorts out a cell. If the cell was fully charged, it will heat up and vent out the "emergency pressure release vent", bypassing the normal vent tube. Also possible the vent tube was not connected.

    I've seen at least one other posting of a Prius going dead while driving due to the 12V battery failing. Well, all lights going on etc. and the car not going again once stopped.

    For the price Toyota charges, a yellow top Optima size 51 battery would be a good replacement. You'd have to rework the mounting hardware and terminals, though.
  • stevegoldstevegold Posts: 185
    Has anyone had to replace the 12V gel cell that starts the computer? After four years I had a problem starting the other day. The dealer can test it and install a replacement if necessary for $125.
    Is there another source of supply? It's a small battery located in the right, back near the spare tire.
  • pathstar1pathstar1 Posts: 1,015
    It's not a gel cell. It's a normal sealed lead acid battery with a vent tube (just like a motorcycle battery).

    If the dealer offered you one for $125 go for it. That's a good price. I've seen others pay $250 and up.

    I haven't seen or heard of another source, though you could check the size (measure it) and go to a battery specialty store. I know the Optima size 51 yellow top would just fit in there, but you'd have to do your own hold-down and terminal modification. It's $220 or so, as well.
  • pathstar1pathstar1 Posts: 1,015
    It's not normal. Was an interior light left on? Hatch not closed properly? A healthy Prius 12V battery can go for a month or longer without use. Do switch off the SKS (smart key system) to reduce drain (button under steering wheel). Do not leave the fob in the car (the car will constantly talk to it). Make sure the fob is at least 100 ft from the car, or in a metal box.

    If none of this helps, purchase a "battery tender". It's a small charger. You attach a lead to the under-hood charging points and plug the lead into the tender when you leave. It keeps the 12V system fully charged.
  • boraboraborabora Posts: 16
    thanks Pathstar1,

    no, i checked every light before i left, and i turned of the SKS, too.

    beside battery tender, what can i do then? changing a battery?
  • pathstar1pathstar1 Posts: 1,015
    The battery may have been damaged before the car was sold. That is, discharged and left that way for a few weeks. A good test is to disconnect the battery and leave it for a few weeks to see if it still discharges. Hard to do, as you want to drive the car.

    Check the battery connections. Make sure they are tight and clean. If they aren't it will never be completely charged. The 12V battery is in the right corner of the hatch area. Remove hatch floor, remove storage bin. Fold black plastic flap forward (away from hatch wall) and lift cover out. You will see the battery.

    Because it's such a small battery, load testers don't work very well. They are designed for larger capacity batteries.
  • jaxs1jaxs1 Posts: 2,697
    I read elsewhere that it is normal because of the battery's very small size and capacity and the solution is to have someone drive the car at least once a week, disconnect the battery, get a battery minder or simply be prepared to recharge the battery when you return from vacation.
  • suirpsuirp Posts: 4
    I disconnect the battery terminal under the hood when I leave my Prius garaged for up to 10 weeks each summer. Reconnect on return and it starts right up.
  • I made a mistake in thinking I could have my old Alpine navigation system installed on my new 2007 Prius. That system worked fine on three previous cars where there was plenty of room for it. But on the new Prius, it seems a gamble whether there is any room at all for the installation. People at the dealer's said there is too much wire and components in the dashboard area. Is it possible to get a look-see at that area without too much trouble?
  • vcgenovcgeno Posts: 5
    I have had my Prius for about 7 months without a problem. A few days ago after parking it 50 degree weather the utility battery died. No doors were open, no lights were on, and I can't figure out what happened. I had it checked out at the dealer and they said there was no problem with the battery or the charging system. It seems to be working OK now. Anyone else have this problem or know what might have gone wrong?

    I also found jump starting the Prius quite an adventure. Standard sized jumper cables are to big for the battery terminal. I had to find someone with a cheap set of cables in order to jump start the car. The slot where the positive terminal is is much too narrow. Anyone have any suggestions for me?

    That said I love the car.
  • stevegoldstevegold Posts: 185
    I have a 2004 Prius. The same thing happened to me twice, the first time after a month or two and the second time three years later. I probably left something on as those are pretty infrequent intervals. You do NOT have to get to the small battery to jump it. There are special terminals under the hood that make it real easy. Look in the book.
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