deathsquad

I got a p0305 and p0300 code on a long trip (CYL 5 & Randome Misfire). My car was idling roughly and then stalled out (Check Engine flashing, VSC ON and OFF illuminated.

I changed the plugs (found coolant in the 5 & 6 valley). I determined there was no coolant leak, cleaned and fired everything up with the new Denso plugs in. She ran fine for an hour and stalled out once more. Soon after, I had check engine flashing, VSC ON and OFF lights illuminated again. I had it towed to my local Toyota dealer and after them saying nothing was wrong with the car, It happened again. I took it back for a second time. Then.....AGAIN so I dropped it off for the third time and they just called me saying they determined it wasn't the plugs or coils but the actual wiring harness itself "must be losing voltage somewhere on its way to the coils" and needs to be replaced.

Now I know this sounds stupid, seeing how I paid 139$ for the diagnostic. It seems like they're just guessing at what it could be. The manager explained that they cannot just splice new wires into a harness since it seems like one is shorting and it will cost a WHOPPING $1,872 for a new one installed. I am at a loss for what to do because I am a poor student. Do you guys have any ideas?

Thanks for your time fellow GS lovers.

-Tyler

GS4_Fiend

iTrader: (22)

If the misfiring started to happen after you changed your plugs, i doubt it's a wiring problem.

angelgs

check the witing plug to the coils they are really fragile might be on of them broken on the inside or not making good conection..... i have the same issue i just gave up car runs fine no issue at all......i replce the plugs next i be ordering the connectors to replace them all 3 are bad so hopefully when i do that next weekend the lights would go out
http://www.toyotapartsexpress.com/pa...FQdk7AodBX0Abw

BigWalt

Ouch, hope you get it figured out.

vijayn

Also the actual wiring could be broken and shorting on another wire or metal intermittently. Try and do a good visual inspection on all 3 sets of wires going to the 3 coil packs. From the heat, the wires plastic insulation breaks off and exposes the copper wires over time.

JeffTsai

iTrader: (1)

Exactly what the other 2 guys said. The plastic connector on the coil packs get brittle over time. A light touch and they break in half. Swap those connectors out and you'll be good to go. If there is still an issue, then maybe the coil pack needs to be changed out.

deathsquad

Thanks for the replies. The clip going on to the plug on the coil was a little brittle but that was in the 1st/2nd cylinder valley. The others looked fine.

I guess I will look at the harness itself. Is it under the passenger front fender like most cars? I hit an exposed railroad tie going about 20mph a while ago and now the wheel well splash guard looks a little loose. Maybe I hit it with enough force to jumble the wiring harness?

Edit:

Do you have a part number/ website you could recommend? Any writeups on this?

angelgs

here is the link for the clips http://www.toyotapartsexpress.com/pa...FQdk7AodBX0Abw

and there is a write up on how to change the connectors in here is really not that hard

deathsquad

"The page cannot be found"

vijayn

The wires for the 3 coils can be found where the coils are. Start from the coil connector and work your way back to the main harness. I'm pretty sure this will be the most likely place where the plastic insulation will be broken/brittle as this is where the heat is.

deathsquad

Now that I think about it, those coil pack connectors were brittle as hell. I dug out a lot of broken black and white plastic out of the spark plug holes. I even saw some RTV goop on the inside of the Cyl 1 and 2 connector as that one was the most broken.

If this is the problem I cannot believe the Toyota tech didn't see that the clips were broken. It's obvious. Do you guys think I would be out of line asking for my $136 diagnosis fee back? I feel like just saying "yeah its the harness, $1800 please" is not a diagnosis, especially since I've missed school and work 3 times to limp the car to them.

Chankeye

i would totally ask for your money back if those connectors turn out to be your problem.

titangts

yeah definitely.. if your car is miss firing its one of three things.. Coil pack, Injector or a spark plug. (well for 98% of the time). If you can change your plugs, you can fix this problem.