Two P0705 codes, but 04 Cruiser works after being towed, so mechanics can't find problem

[pinto]

[First post, please be gentle.] I have a 2004 Land Cruiser, with a little more than 200K on it, that has been an absolute rock. In January, though, I was driving it and all the gear lights came on. First the backup camera came on (which doesn't usually work), then R lit up, then the P, then ALL the lights, then it fell out of gear. I had pulled over, turned off ignition and back on, same thing, couldn't put it into gear, assumed my transmission was toast. Had it towed to a shop in Leadville (I was out of town when it happened), and they called me the next day and said they couldn't find anything wrong with it. It started fine, drove fine, there was a code for the transmission range switch, but it wasn't definitive (or something like that). They weren't sure if the switch was bad or not, but they replaced it because it was the cheapest thing to do, and hey, maybe that was it.

Fast forward to last week. My son started it, and all those lights went on, it wouldn't go into gear, etc. He let it sit, tried the next day, still not going into gear. We brought a code reader to his garage, thinking maybe just clearing the code would help (still the P0705). Nope. So, towed it to our own mechanic (Denver area) this time. Naturally, the car worked fine again. (I'm wondering if something about towing it?? Getting it into neutral? is that fixing the issue?)

They spent 2 days trying to find the issue but couldn't. The switch is fine, hasn't failed. My next step is to call some dedicated Toyota places around here, but has anyone experienced anything like this? any ideas?

 

[khymel5]

[First post, please be gentle.] I have a 2004 Land Cruiser, with a little more than 200K on it, that has been an absolute rock. In January, though, I was driving it and all the gear lights came on. First the backup camera came on (which doesn't usually work), then R lit up, then the P, then ALL the lights, then it fell out of gear. I had pulled over, turned off ignition and back on, same thing, couldn't put it into gear, assumed my transmission was toast. Had it towed to a shop in Leadville (I was out of town when it happened), and they called me the next day and said they couldn't find anything wrong with it. It started fine, drove fine, there was a code for the transmission range switch, but it wasn't definitive (or something like that). They weren't sure if the switch was bad or not, but they replaced it because it was the cheapest thing to do, and hey, maybe that was it.

Fast forward to last week. My son started it, and all those lights went on, it wouldn't go into gear, etc. He let it sit, tried the next day, still not going into gear. We brought a code reader to his garage, thinking maybe just clearing the code would help (still the P0705). Nope. So, towed it to our own mechanic (Denver area) this time. Naturally, the car worked fine again. (I'm wondering if something about towing it?? Getting it into neutral? is that fixing the issue?)

They spent 2 days trying to find the issue but couldn't. The switch is fine, hasn't failed. My next step is to call some dedicated Toyota places around here, but has anyone experienced anything like this? any ideas?

I have indeed experienced similar issues with P0705. The bad news is that I never figured it out. Here's a link to my thread from when it happened.

This happened back in September 2016 shortly after I purchased my used '07 LX with 120k miles. I ended up clearing the code, and it hasn't returned since then (6 months / 5k miles ago). I have a few theories about what the problem might have been:

1) It may have been related to low voltage. A few weeks after this happened, my alternator started whining, and during cold starts, cranking was fairly slow. The battery was 7 years old. Replaced with a remanufactured denso alternator and a northstar group 27f AGM battery.
2) The BMW dealer I bought it from mentioned that they "thoroughly" steam cleaned the engine bay. Not something I would ever do. Might have ended up squirting water somewhere undesirable.
3) I disassembled the center console to check the connections and switches related to the shifter, and check for spilled drink residue. I didn't find any spilled drink residue, but maybe the process of unplugging and replugging everything fixed some loose connection.
4) Shortly after this, I did a full drain (through the cooling line) and refill of the ATF. Doubtful that this is related, but maybe?

 

[khymel5]

I had a look at the FSM. It seems that most of the diagnostics focus on the park/neutral position switch, which is part # 84540-04010, and is around $200. The other possible problem is a misadjusted shift cable.

Btw, it took me quite a bit of research to figure this out, but: the name "park/neutral position switch" (PNP) is a misnomer. This switch does not merely report whether the transmission is in park/neutral or not. It reports the full longitudinal (forward and backwards)range of the shifter. There are two additional switches in the center console, which are the 4 -> D switch, and the 2 -> L switch. If you notice, 4 and D share the same longitudinal position, as do 2 and L. So from the perspective of the PNP switch, 4 and D are the same position, as are 2 and L. This is why the two additional switches are necessary in the center console. These interior switches detect the horizontal position of the shifter in these two cases.

Here's the FSM page with the details for testing the PNP switch with a multimeter. Since this is an intermittent malfunction, the multimeter test probably won't find any problems. It's still a good idea to get under the truck and inspect the PNP switch and see if there is any visible damage.

Edit: I reread your post. It's interesting that you mentioned your backup camera doesn't usually work, but during the malfunction it started to work. This probably indicates an ongoing problem with your PNP switch not being able to properly detect reverse. If you can still reproduce this problem (backup camera won't turn on), then you should be able to verify that you have a bad PNP switch by doing the terminal 2 -> 3 continuity test in the table above.

 

[khymel5]

Sorry for three posts in a row, but I can't stop researching this issue

I came across this TSB for P0705 in 2005-2009 Tacomas, which use the same PNP switch as us:

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 reminds me of the water ingress issue that some 100 series owners have seen with the drivers side kick panel. If I recall, this can be caused by improperly installed windshields, clogged sunroof drains, and possibly some other sealing problems.

My question for pinto is: was it raining when P0705 first appeared for you?

 

[04UZJ100]

Check to see if there is any corrosion on the leads and connectors between the cab and the transmission itself. Physically go underneath, disconnect and inspect everything electrical going to the trans.

Lots of ghostly trans issues related to corroded external electronics.

 

[pinto]

Sorry for three posts in a row, but I can't stop researching this issue

I came across this TSB for P0705 in 2005-2009 Tacomas, which use the same PNP switch as us:

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 reminds me of the water ingress issue that some 100 series owners have seen with the drivers side kick panel. If I recall, this can be caused by improperly installed windshields, clogged sunroof drains, and possibly some other sealing problems.

My question for pinto is: was it raining when P0705 first appeared for you?

It was snowing the first time. The second time, it was in the garage, but I'll have to check back on the weather the day it happened.

 

[pinto]

Ok, yes, the second time, it was a snowy/rainy weekend, as well.

I know one thing the shop told me was that they attempted but could not get that PNP to fail. I don't know what all that entailed; I have asked for a list of stuff they already checked and ruled out.

 

[VirginiaSlim]

I just got the P0705 code on my 2004 LX470. It's snowing today and the roads had not been cleared when I was driving. The LX sat for a couple hours, then the check engine and VSC lights came on and the P0705 code showed when I checked OBDII. In mine, the P and the D are both lit up at the same time in the gear indicator on the dash. Car otherwise drives fine. Going to continue investigating. I may just clear the code and see if it comes back up.

Did you resolve your issue?

 

[VirginiaSlim]

I just got the P0705 code on my 2004 LX470. It's snowing today and the roads had not been cleared when I was driving. The LX sat for a couple hours, then the check engine and VSC lights came on and the P0705 code showed when I checked OBDII. In mine, the P and the D are both lit up at the same time in the gear indicator on the dash. Car otherwise drives fine. Going to continue investigating. I may just clear the code and see if it comes back up.

Did you resolve your issue?

Update: Yesterday morning I still received the check engine, VSC, and TRAC lights and the P0705 code. However, when I placed in gear "D" the gear indicator no longer simultaneously displayed "P" lit up. Drove the truck to work and it drove fine. After sitting in a parking garage all day, started it up and I'm not getting the engine, TRAC, or VSC lights anymore. I now assume the issue was moisture related.

 

[flintknapper]

Update: Yesterday morning I still received the check engine, VSC, and TRAC lights and the P0705 code. However, when I placed in gear "D" the gear indicator no longer simultaneously displayed "P" lit up. Drove the truck to work and it drove fine. After sitting in a parking garage all day, started it up and I'm not getting the engine, TRAC, or VSC lights anymore. I now assume the issue was moisture related.

You might want to take a peek at your ECU and see if there is any evidence of water/moisture there (windshield leak).

 

[Skidoo]

Might check for rodent chewed wires, that can cause unusual behavior.

 

[jayLC1]

I just got the P0705 code on my 2004 LX470. It's snowing today and the roads had not been cleared when I was driving. The LX sat for a couple hours, then the check engine and VSC lights came on and the P0705 code showed when I checked OBDII. In mine, the P and the D are both lit up at the same time in the gear indicator on the dash. Car otherwise drives fine. Going to continue investigating. I may just clear the code and see if it comes back up.

Did you resolve your issue?

I had this exact deal, got "P" and "D" at the same time, but eventually resolved. I had the codes cleared (I was out without my code reader).

The strange circumstance is that this happened on the first start after my windshield was replaced.

 

[VirginiaSlim]

this happened on the first start after my windshield was replaced

From my anecdotal research on this forum and elsewhere, it seems this code/issue is often correlated to a replaced windshield, leaking windshield, and moisture getting into the ECU from the windshield or another location. Did you have rain or wash your truck after the windshield replacement and before the check engine and code? I haven't had the problem since. I suspect it was due to the heavy snow and ice melting by my windshield and possibly getting into the ECU at some access point.

 

[jumptrader]

Just saw the P0705 code 2 days in a row (heavy raining in Northern California). We've never had this much rain in the past 2 years, and must definitely be moisture related.

Does anyone have any tips on how to better moisture proof the ECU?

Thank you!

 

[wetcoastlexus]

Just saw the P0705 code 2 days in a row (heavy raining in Northern California). We've never had this much rain in the past 2 years, and must definitely be moisture related.

Does anyone have any tips on how to better moisture proof the ECU?

Thank you!

Hi there - new here - I have same issue - did you resolve ECU moisture issue- moisture proof