Hello Everyone,
I have owned camry's for a VERY long time, and have yet to encounter this issue. I believe this is my 6th or 7th camry, all of which I finally traded in after 350k miles, so needless to say, I trust them.
This issue I thought would be a simple google fix, but alas, it is not.
2 weeks ago, I started to change out the Spark plugs and Coil Packs, and of course doing this, I disconnected the negative battery terminal.
I did this mainly for routine upkeep, but there was a temporary code popping up for the ignition coil # 3. with no other symptoms or issues, Needless to say, I actually ended up ordering the wrong packs, so I just changed the spark plugs, air filters, and the oil and filter.

However, after I reconnected the battery cable (after the spark plugs, before the oil and filter changes), the radio would not come on. There is NOT a security notice, there is just Nothing at all, no lights etc., nothing. I thought fuse, So I replaced the Radio Fuses, the radio did not come on, no power to it of any kind, BUT the clock, cigarette lighter/charger, and other similar fuse items function properly. In checking these fuses, note, the only code this car ever displayed was that coil #3, ONE time, cleared it, and it never returned. After checking the fuses, and NONE of the fuses needed to be replaced, but after checking the Instrument cluster went off with no power at all other than the turn signals, seat belt indicator, and indicator that the headlights were on. I ran the codes again during this and came up with a plethora of codes, however, the one that is sticking is P0500, which online seems to be costly to repair, and then once or twice in repeating the code check after clearing a code for B1660 (something about passenger airbag) popped up and then went away when I cleared.
I thought, maybe the battery terminals were just so corroded that this was possible cause of concern, and I was right, the Positive side was nearly corroded to nothing, so I replaced it, and the ground side was in really good shape. The P0500 code is now listed as a permanent code, and the radio still does not work, and now the battery indicator light or charging system fault indicator ( the battery) is lit up, and will not go away. I tried disconnecting negative, and unplugging the alternator and making sure the connection was secure, and then reconnecting and the battery light is still on. I am lost, and not sure what to do, I am NOT taking it to a dealer... I bought the car over 2 years ago for a great cash price, and have never had to do anyting other than TLC routine stuff. It now has 292k miles on it, all high way, I do know that i hit a pot hole or something months back and dented the oil pan and filter housing; however, I had the filter housing replaced, and they said the oil pan dented wasn't a major concern unless it was leaking oil, so I ordered the new oil pan, but have not had it installed yet, or attempted to install myself, because it has never had an issue with consuming or burning or running low on oil. I will get to that eventually.
I thought the coil packs might help with the fact that however, in the last 3-5 months, I went from 28-30 mpg hwy to 19-22mpg hwy. I've done every other mpg related TLC I can think of without replacing serpentine belt, transmission flush again, and the coil packs. The belt is due again in about 10k miles I believe, and the trans flush was just done at 270k miles, I am not sure when the coil packs were done if ever, but the new packs are on their way and that will be resolved.


So sorry for the novel, but can someone please help???
1.) disconnected battery for spark plugs, resulted in No Radio power or lights etc.
2.) checked fuses, resulted in no instrument cluster activity at all, discovered that I'd left a small 7.5 fuse unplugged, and the instrument cluster now works perfectly.
3.) in the middle of the instrument cluster fiasco, the P0500, code came up and is now saying "permenant", and other codes appeared, but then went away without returning after I cleared them with an OBD tool.
these codes that didn't return were: P0500 (vehicle speed sensor circuit), C1201 (engline control sys malfunction), C0365 (deceleration sensor), C1241 (low or high powe supply voltage). C1333 (open circuit in left rear speed sensor circuit). I believe that all of these other issues were a result of that fuse I apparently missed to plug back in. I discovered it after driving the car about 30 miles. so, After plugging that back in, the cluster works, and the only code that persists is P0500, and now the battery (charging system) indicator.

Lord, I also own a 2006 prius, that I picked up dirt cheap last year thinking it would be a fun project car... HAHAHAHA negative.... 3,500 later I've rebuilt everything but the frame and paint job lol

Thanks in advance for any assistance, and I promise all of my posts and replies will not be this lengthy.

Thanks guys,
- Wayne the confused and annoyed toyota-aholic lol

 

Are you stating the car now gets poor gas mileage?

P0500 is speed sensor. Does the speedometer work OK?

If the battery cable connection was bad. The alternator could have lost electrical connection with the battery and the alternator could have been damaged. Alternators don't like being disconnected from the battery.

Get a voltmeter. Check battery voltage engine off and running at say 2000 RPM. Engine off will be battery voltage. Engine running should be around 14 to 15 volts as the alternator works.

How is the engines performance, idle (hot and cold), etc? Low MPG could be a failing 02/AF sensor, bad ETC (coolant temp sensor), etc.

Some years of Toyota required a security code to reset the radio. Suggest reading the owners manual to determine if your cars year is one of them. If you don't have a manual Toyota has them at the site below:

https://www.toyota.com/owners/resour...owners-manuals

 

Hi, The car has been getting poor gas mileage for months now, That is why I unplugged the battery to replace the coil packs and spark plugs, going through routine TLC in order to attempt improving mpg.

After, replacing spark plugs and coil packs, the radio will not turn on, I have disconnected the battery again, and reset everything, there are no blown fuses or relays, my next step is just to replace the entire radio itself, I guess...

The P0500 code has not come back as a current code, it is just left in the system as a permanent code, I am unsure how to clear permanent codes in the background, my obd II doesn't clear the perm codes it seems. It runs and drives fine. I'm guessing that the P0500 code occurred in the process of testing fuses... because it never had any power or speed issues. I did have to replace the oil filter housing a few months back, and they told me that the oil pan was dented in, but not cracked or leaking, but I ordered the oil pan to replace any way, but have not yet attempted that.


So for now my main issues are:
1. figure out WHY the terrible MPG (18-23mpg hwy)
2. figure out what is going on with the radio
3. find a way to remove the perm code hiding in the background, without the "sketchy" (method of disconnecting the battery and connecting neg and pos cables together away from battery for 30 minutes) This is what I read on some forum, it just doesn't sound entirely secure for the other car settings and safety etc.

Thanks for any help!

 

Oh, One more ting I almost forgot, after repairing the battery terminals, and discovering the perm code, the battery (charging system) light has remained lit. I took it to auto zone, and they tested the battery, alternator, and starter... all of these tested perfect. and the battery has good connections, but the battery light stays on... no symptoms as a result of it though.

 

1) Poor mpg could be failing O2-A/F sensor, plugged emission converter, issues with other sensors such as ETC, MAF. problem PCV system, EGR. etc. Something as simple as a broken vacuum hose or unplugged wire, cracks in engine air intake hose, exhaust leaks, etc. Have you checked the air filter to determine if say rodents have built a nest?

2) Read your owners manual to determine if the radio has anti-theft security system needing a security code to reset it after power is disconnected.

3) Toyota uses both standard generic ODB codes and their own proprietary codes. The P0500 is a generic code.

Read up on laptop and smart phone usage and ELM327 software. The laptop or phone can be connected to the ODBII port with something called a dongle (hard wire) or a plug in wireless device for wi/fi. Having a good scanner will allow viewing real time car/engine computer data which can help narrow down the problem.

Does the car have ABS? Its possible the P0500 code could be related to traction control. A good code reader can scan all items related to traction control.

Disconnecting the battery on later model Camry is not going to reset codes. You need to do this manually or if the problem has been fixed, let the computer do it.

Toyota has a website where for $20 you can get 2 day access to all factory service info available and download what you want. Here you can get detailed info P0500 and a wiring diagram for the radio showing all fuses.

https://techinfo.toyota.com/techInfo....toyota.com%2F