P0705 Park Neutral Switch

Got a P0705 code on my 06 PreRunner with 50k miles. No alterations to the wiring have been made. The TSB says:
Summary:
TOYOTA: AUTOMATIC TRANSMISSION/TRANSAXLE. SOME VEHICLES MAY EXHIBIT A MIL ON CONDITION WITH DTC P0705 (TRANSMISSION RANGE SENSOR CIRCUIT MALFUNCTION (PRNDL INPUT)) STORED. COMMON SYMPTOMS WITH THIS DTC CAN INCLUDE POSSIBLE DELAYED ENGAGE ( NHTSA ITEM NUMBER - 10030909 )

I do get the delayed engage (4 or 5 secs) when moving from reverse to drive. If I shift it fast enough it's ok. Took it to the dealer because the TSB says POWER TRAIN:AUTOMATIC TRANSMISSION" but I was told it was not covered under the powertrain warranty. They said the fix was to ...get this...change the complete front end wiring harness, as well as Junction Block #1. The service rep couldn't tell me where the "Junction Block #1" was located. All he could tell me that it would run between $1500 and $2000 to repair it. Anyone else ever had this issue? Any recommendations would help.

 

My 2005 has just been diagnosed with this problem re: TSB 0277-09 requiring the replacement of the main wiring harness to fix it. Quoted $2400. I am very upset because this is clearly a design or manufacturing problem and not something that is due to normal wear. Corrosion in a connector or wiring that should not happen and requires replacement of the entire harness. I am no longer a happy Tacoma owner. Any suggestions appreciated.

 

BoBo, Good luck with this one. I too have tried to explain to Toyota and the dealership that this fix(wire harness replacement) was a bunch of crap. They informed me that the only fix they would do was the harness replacement for this code (PO705). I explained to them that this truck has never had any water in it nor been off roading. Didn't seem to matter to them. I am up against the wall on this one because my drivetrain warranty is going to end soon. I was able to talk them down some on the price. But get this, the harness is on national backorder and mine just came in after almost 3 months. I don't think the harness is the problem, but they have me by the short hairs. Do you have the delayed shift problem? I have found out that I can shift from Park to Drive really fast and there will be no delay. Don't know what that means, but it sure as hell doesn't sound like a wiring issue. Good Luck

 

I just read the whole tsb. The junction block is in the left kick panel by the drivers feet. It says to look for corrosion there. They don't really address where the water is coming from. It looks like the harness that is getting changed includes the grommet where it goes through the firewall. Maybe the water is following the wires from under the hood? Maybe you guys should check that connection yourselves and shoot some electrical contact cleaner in there?

 

http://www.scribd.com/doc/18857706/TSB027709

Link to tsb, down towards the bottom there is a picture of the junction block.

 

Joes06...been there done that. Inspected both ends. No sign of corrosion or dirt. Clean as a whistle. The tsb states that if liquid or corrosion is observed, then the wire harness should be replaced. The dealership did not even ck this on their own. They put their reader on and that was it. They went straight for the high dollar fix ($1500+++)without even checking out the other possible causes. i.e. the PN safety switch that is mounted on the side of the transmission. ($300) Supposed to get this done when my assigned service writer gets back from vacation in a week. Will give you an update then. Not sure if they will tell me the truth on what they fixed, but will make sure I ask for the bad parts.

 

Per Rusty and Joe's posts I have located and checked the connector and terminal block for liquid and/or corrosion. I see none. How this can happen inside the vehicle is a good question. I will check with the dealer again to see how deeply they checked out the problem. After being told of the problem I was speechless and did not ask enough follow up questions. Now that I have a better understanding of the issues I will go back. Thank you.

 

I do not have the delayed shift problem. My symptom is simply increased force needed to move the shift lever. Sometimes the dash indicator goes dark as well.
It does go into gear ok with extra pulling on the lever. On the way to the dealer the check engine light came on for the first time and per the dealer showed the code related to this TSB. Since that time the light has gone out and the problem has not happened again but I do not know when it will come back.

 

Armed with all this information I went back to the dealer to ask many questions regarding this TSB 277-09. After talking to the service manager and the tech who looked at the truck I found out that all they know about the issue is what is in the TSB. It says replace the harness and terminal block so that is what they will do. The tech and I took apart the connector, which he said he had done, and one of the silver pins in one of the connectors was slightly discolored. This connector was not J1 as specified in the TSB. After this I cancelled the repair order. I plan to use some contact cleaner on the connectors and reconnect them a few times to wipe the contacts. I may put some dielectric grease on the contacts to protect them from moisture but these connectors are inside the car so they do not get wet with rain or road splash. I would like to find someone at Toyota that understands this problem but I think that is impossible because the only referral I could get from the SM is to contact California Customer Service.
Thanks for the feedback.

 

BoBo, I am scheduled to get the harness installed tomorrow. I will post what (they said) was done and the outcome.

 

The code means that the ecm is recieving two signals at the same time. It's getting this information from the neutral safety switch. It could just be the switch. Maybe question the dealer about how they eliminated the switch?

If it's physically difficult to move the shift lever, then perhaps the switch itself is binding up? Maybe it's come apart inside? They are usually mounted on the transmission.

 

Through help from my dealer I received this feedback from Toyota:


Certain 2005 Tacoma Wiring Harnesses can have water contamination due to
inadequate sealer applied around the engine room grommet. This contamination
can lead to erroneous gear position inputs to the transmission control module.
Because the inputs to the TCM are conflicting, the vehicle will set a DTC P0705
and the customer may experience harsh engagement of the gears as the TCM
struggles to interpret what gear the vehicle is actually in. The new harness
has improved water sealing around the engine compartment grommet that prevents
the fluid contamination.


This is a better explanation of the source of the contamination and the computer confusion caused by the wrong inputs. Now I would like Toyota to admit it is a design/manufacturing issue and provide a simpler fix like additional sealer on the leak and cleaning of the harness contacts. I am still trying to elevate the issue with Toyota.

 

BoBo,
Got my 06 back friday. They changed out the harness and the junction block. The code light was off and the shift problem was not there. While driving home, it did completely die on me. Called the dealer and they sent a wrecker and picked it up. They said one of the connecters came loose. Got it back this morning. It seems to be doing fine. I did check to see if they messed with or changed out the neutral safety switch, but they didn't. I was also having a "clunk" while in low rpm in high gear when I would give it gas before, like there was some play in the driveshaft or trannie, they told me they couldn't fix that until they replaced the harness in case they were related. I did notice, they put a new front driveshaft in, although there was no mention of it on the service receipt. They were able to talk Toyota into doing a 50/50 deal with me. So my cost was $1250 to get this design flaw fixed. Let me know if you if you get anywhere with Toyota, I sure could use that $1250 on something else. Good Luck.

 

I posted on another thread about my issue (code p0705) and what Toyota did for me. (See will the dealer help?) So, here is my question to you guys with the problem. Did you have a remote starter installed prior to the check engine code and the reverse-to-drive hesitation. Here is why I ask.

Last week Toyota replaced my harness and everything worked fine. Except they had disconected my PIAA lamps and my remote starter. The reverse-to-drive issue was completly gone. Yesterday my installer connected the remote starter back. ( this guy has done 5 cars in my family, 3 Toyotas) after he re-installed the remote starter the issue came back. Check engine light came on and there was a hesitation between reverse and drive. I called my installer as soon as i noticed it and he came right over and removed the remote starter. I disconected the battery for about 8 minutes and then reconected. When I started the car the check engine light was off and there was no issue when shifting. I've been driving the car all day and no more issues.

I will be notifying Toyota about this. They should have sugested or asked if I had a remote starter installed. Should have thought of it before it cost me $1000 for the repairs. My installer will be looking into the issue and I will post a solution if we find one.

Again, if you installed a remote starter and then your reverse-to-drive issue started, try removing it before spending the money.

Sato

 

Satodog, I do not have a remote starter installer.

After visiting the dealer again after the $2000 wiring harness diagnosis and realizing that the connector that supposedly causes the problem is located on the left kick panel inside the truck I cancelled the harness order and did the following. I took the connector block apart and used contact cleaner on it and reinserted the harness plug several times to wipe the contacts. I really did not see any corrosion on the contacts. Second I sealed the bulkhead opening where the main wiring harness comes into the interior from the engine compartment using a tie wrap to bring the rubber boot close to the harness and waterproof tape. It has been several months and the shifting has been fine. I tried again to get some reasonable response form Toyota but it is a black hole.

 

Hey bobo, that's really helpful information, thanks!
I've had the light come on with this code (and go away again after a few days) after a rainy roadtrip to Canada. I'll check out the connector and clean it according to your guidance.

 

I finally got around to doing this after I got P0705 again along with other codes and mysterious warning lights like RSCA off. I removed the kick panel and sure enough found water behind it. We get floods during the winter around here and apparently I'm not always crossing them slowly enough. The only place where the water could have come in is along the wiring harness from the engine compartment. I followed bobo's instructions: disconnected and dried all the connectors, sprayed them with contact cleaner, plugged them in/out several times and put everything back together.
Then I sealed off the rubber boot in the engine compartment with a ziptie and tape like bobo, done. Some of the connectors are hard to reach but it sure beats dropping 2 grand at the dealer. I'd still like to see what the new OEM harness looks like, though. Maybe someone can take a picture and post it here.
We've had lots of rain lately and I did a few 'spirited' water crossings and so far everything's working fine, knock on wood, no trouble codes or warning lights.
Here's hoping that the truck is now waterproof, after doing the rear diff mod and this project.

 

i just got the code p0705 on my truck today.We put a new drive shaft in my truck i did notice the floor was wet and and my shifter is hard. i am going to try the PN safety switch that is mounted on the side of the transmission.

 

does anyone know where or have a pic of that part

 

The link that joes06tacoma posted appears to have pictures of the junction block. I am planning on trying what Bobo did this weekend.

BTW I do not have a remote starter installed either.