P0705 code and alternator problems. Is my logic sound?

[robguitargod1]

Update: PROBLEM SOLVED P0705 code and alternator problems. Is my logic sound?

Vehicle is an '05 SR5 4.0L

So I'm driving yesterday and BAM, most of the dash lights turn on and I get a CEL. I scan it and it comes back P0705 'Transmission Range Sensor Malfunction.'

I also notice that the gear shift indicator on the dash is not highlighting what gear the vehicle is in. In the picture below the truck in in DRIVE, but 'D' is not highlighted. Hmmmm....

<a href="http://s816.photobucket.com/user/robguitargod12/media/4runner%20problems/20140512_102616_zps0cd67d77.jpg.html" target="_blank"><img src="http://i816.photobucket.com/albums/zz85/robguitargod12/4runner%20problems/20140512_102616_zps0cd67d77.jpg" border="0" alt=" photo 20140512_102616_zps0cd67d77.jpg"/></a>

Aside from the CEL and gear shifter indication, the truck drives perfectly normal.

Today however, it seems that the alternator is not charging. While running battery voltage is only 11.8 volts, telling me that the alternator isn't producing current. The truck is currently dead and will not turn over.

So, here's my thoughts. The 2 problems (the CEL, and the alternator) seem to be independent of each other, would you agree?

The CEL might be remedied with this, but I haven't done any investigating:

T-SB-0277-09

Is there any other reason for the engine to be running, but the alternator not functioning?? Besides 'It's dead' of course. I cannot think of any besides a fuse or relay, yet as with the CEL I haven't done any investigation.

So for the CEL P0705 I'm going to check connections at the gear shifter, kick panel, and transmission.

For the alternator I'm going to check some fuses, and possibly pull the alternator to have it tested.

Would you guys agree? Disagree? Any suggestions before I start probing around?

 

[BlackWorksInc]

Well I would start with the alternator first, I don't know if Autoparts stores use hand-held testers like we do at work that can check alternator function as well (our Midtronics tester does and gives a printout.)

You can check for voltage and see if it increases with RPM (about 2500-3k should see it increase with the vehicle electrically loaded), if you have access to the FSM and/or EWD I would go ahead and check if the connections to the alternator are good and the signal wire is function properly as the ECM does have some control over that. It wouldn't hurt to also have the battery tested, typically alternators I see alternators fail due to trying to charge up failing batteries and being over worked, that's not to say they don't go bad by themselves; just that there's usually a reason the alternator bugs out. I would try and get the alternator fixed first and then clear all the DTCs and see if the condition returns, modern vehicles are very finicky and quirky when battery voltage becomes unstable (which can happen when the battery cannot properly smooth out voltage and/or the alternator cannot provide proper voltage) after that I would start on the P0705 after we've stabilized the supply voltage. The main reason is because without a stable system voltage you can't properly test any electrical system on the vehicle and to do so could lead you to misdiagnose the vehicle, its always recommended you try and start your diagnostics after you've stabilized the vehicle as best as possible.

As for the transmission, that TSB is for a Tacoma but it wouldn't be a bad idea to use it as a guideline for diagnostics since the powertrain should be the same (though the wiring harness is somewhat different) and your symptoms seem similar. At this point you're gonna wanna see if you can find the connectors for the shift sensor to check if it is functioning properly and then trace the wiring harness back to the ECM. That way we can rule out damaged wiring harness, I would recommend both a Resistance Test and also check how voltage flows with the circuit is activated (the reason is because you can have a single strand of copper show a good connectivity, but when voltage is applied the circuit may not function properly, so doing both is a better diagnostic test.)

 

[robguitargod1]

Battery voltage was dropping no matter what RPM the engine was at.

Also, the HVAC and above display are not functioning.

 

[MikeInNH]

If you're reading 11.8 volts when the engine was at about 1500rpm's or higher...then the alternator is toast.

The CEL may or may not be related. I'd fix the alternator first...and then see what happens. It may actually fix the CEL problem.

 

[robguitargod1]

It was a 15A IGN fuse under the dash.........A DAMN FUSE caused all those electrical gremlins!!!

I worked all night with no luck (And missed the Hawks game) Next morning before work I started to rethink things. I pull out my Fluke77 and start continuity testing every fuse starting under the hood. Everything was good there.

Then I started under the dash and found this fuse blown:

<a href="http://s816.photobucket.com/user/robguitargod12/media/4runner%20problems/20140514_090459_zps1aa856b5.jpg.html" target="_blank"><img src="http://i816.photobucket.com/albums/zz85/robguitargod12/4runner%20problems/20140514_090459_zps1aa856b5.jpg" border="0" alt=" photo 20140514_090459_zps1aa856b5.jpg"/></a>

I immediately did some current and short testing. Everything seemed fine so I replaced it and BAM, everything's good! Alternator is charging @14V, no CELs, no problems.

So remember, check your fuses because this little guy caused:

- 11.7V across battery while running
- P0705
- dead battery
- HVAC dead
- Display dead
- Gear selector on dash not highlighting what gear the vehicle is in
- no reverse lights

Now we're back to normal!

<a href="http://s816.photobucket.com/user/robguitargod12/media/4runner%20problems/20140514_102700_zps214d8a04.jpg.html" target="_blank"><img src="http://i816.photobucket.com/albums/zz85/robguitargod12/4runner%20problems/20140514_102700_zps214d8a04.jpg" border="0" alt=" photo 20140514_102700_zps214d8a04.jpg"/></a>

 

[BlackWorksInc]

Doesn't surprise me, that was why I had suggested to see if the FSM showed a load control circuit. I should have mentioned check the fuses as well though (its one of those things that seems obvious to me so I had assumed you already did it.)

The next thing you need to do is find out what else runs off that circuit and keep an eye on it. Fuses don't blow by themselves, so something had to take the fuse out; maybe it was a one time deal, or it could indicate something on that circuit starting to fail.

 

[turtle_runner]

It was a 15A IGN fuse under the dash.........A DAMN FUSE caused all those electrical gremlins!!!

I worked all night with no luck (And missed the Hawks game) Next morning before work I started to rethink things. I pull out my Fluke77 and start continuity testing every fuse starting under the hood. Everything was good there.

Then I started under the dash and found this fuse blown:

<a href="http://s816.photobucket.com/user/robguitargod12/media/4runner%20problems/20140514_090459_zps1aa856b5.jpg.html" target="_blank"><img src="http://i816.photobucket.com/albums/zz85/robguitargod12/4runner%20problems/20140514_090459_zps1aa856b5.jpg" border="0" alt=" photo 20140514_090459_zps1aa856b5.jpg"/></a>

I immediately did some current and short testing. Everything seemed fine so I replaced it and BAM, everything's good! Alternator is charging @14V, no CELs, no problems.

So remember, check your fuses because this little guy caused:

- 11.7V across battery while running
- P0705
- dead battery
- HVAC dead
- Display dead
- Gear selector on dash not highlighting what gear the vehicle is in
- no reverse lights

Now we're back to normal!

<a href="http://s816.photobucket.com/user/robguitargod12/media/4runner%20problems/20140514_102700_zps214d8a04.jpg.html" target="_blank"><img src="http://i816.photobucket.com/albums/zz85/robguitargod12/4runner%20problems/20140514_102700_zps214d8a04.jpg" border="0" alt=" photo 20140514_102700_zps214d8a04.jpg"/></a>

Mine keeps doing the same problem. I changed the fuse. Car was fixed. One week later. Same problem.

 

[eXstasy]

It was a 15A IGN fuse under the dash.........A DAMN FUSE caused all those electrical gremlins!!!

...

So remember, check your fuses because this little guy caused:

- 11.7V across battery while running
- P0705
- dead battery
- HVAC dead
- Display dead
- Gear selector on dash not highlighting what gear the vehicle is in
- no reverse lights

Now we're back to normal!

Old thread but I just wanted to say thank you very much for posting this. I had the same exact issue and I was scratching my head for the longest time wondering why.

I had already spot checked the fuses that I thought were related to the reverse lights and gear selectors, but did not go through every single one. Now I know that I should have.

I even initially gave up and ordered the transmission neutral safety switch to potentially resolve P0705 prior to coming across this thread.

 

[PickleRiiiick]

It was a 15A IGN fuse under the dash.........A DAMN FUSE caused all those electrical gremlins!!!

I worked all night with no luck (And missed the Hawks game) Next morning before work I started to rethink things. I pull out my Fluke77 and start continuity testing every fuse starting under the hood. Everything was good there.

Then I started under the dash and found this fuse blown:

<a href="http://s816.photobucket.com/user/robguitargod12/media/4runner%20problems/20140514_090459_zps1aa856b5.jpg.html" target="_blank"><img src="http://i816.photobucket.com/albums/zz85/robguitargod12/4runner%20problems/20140514_090459_zps1aa856b5.jpg" border="0" alt=" photo 20140514_090459_zps1aa856b5.jpg"/></a>

I immediately did some current and short testing. Everything seemed fine so I replaced it and BAM, everything's good! Alternator is charging @14V, no CELs, no problems.

So remember, check your fuses because this little guy caused:

- 11.7V across battery while running
- P0705
- dead battery
- HVAC dead
- Display dead
- Gear selector on dash not highlighting what gear the vehicle is in
- no reverse lights

Now we're back to normal!

<a href="http://s816.photobucket.com/user/robguitargod12/media/4runner%20problems/20140514_102700_zps214d8a04.jpg.html" target="_blank"><img src="http://i816.photobucket.com/albums/zz85/robguitargod12/4runner%20problems/20140514_102700_zps214d8a04.jpg" border="0" alt=" photo 20140514_102700_zps214d8a04.jpg"/></a>

Dude!!!! You saved my a$$ on this one!! Same exact things where happening to my 05 4runner... and exact same solution, the 15 amp ignition fuse under the dash.

You mentioned you where messing with a trailer, well I also was using a trailer when my issue happened. When I backed up to the trailer I had my emergency brake on and gave it gas so it slowly inched under the hitch of the trailer.. then I had mounted my trailer and plugged in the 7 pin.. now what I’m thinking may have caused it was either faulty trailer wiring , because the wiring on this trailer has been kinda sketchy lately... or it’s because I kept it in reverse for about 15 mins while I was talking and didn’t put it back into park , so maybe that over used the circuit I am not sure on why that fuse popped but I put a new one in and all is well!!

Thank goodness for your post because I was freaking out, and it took me about 20 mins of researching to find this

 

[pjbrownva]

It was a 15A IGN fuse under the dash.........A DAMN FUSE caused all those electrical gremlins!!!

I worked all night with no luck (And missed the Hawks game) Next morning before work I started to rethink things. I pull out my Fluke77 and start continuity testing every fuse starting under the hood. Everything was good there.

Then I started under the dash and found this fuse blown:

<a href="http://s816.photobucket.com/user/robguitargod12/media/4runner%20problems/20140514_090459_zps1aa856b5.jpg.html" target="_blank"><img src="http://i816.photobucket.com/albums/zz85/robguitargod12/4runner%20problems/20140514_090459_zps1aa856b5.jpg" border="0" alt=" photo 20140514_090459_zps1aa856b5.jpg"/></a>

I immediately did some current and short testing. Everything seemed fine so I replaced it and BAM, everything's good! Alternator is charging @14V, no CELs, no problems.

So remember, check your fuses because this little guy caused:

- 11.7V across battery while running
- P0705
- dead battery
- HVAC dead
- Display dead
- Gear selector on dash not highlighting what gear the vehicle is in
- no reverse lights

Now we're back to normal!

<a href="http://s816.photobucket.com/user/robguitargod12/media/4runner%20problems/20140514_102700_zps214d8a04.jpg.html" target="_blank"><img src="http://i816.photobucket.com/albums/zz85/robguitargod12/4runner%20problems/20140514_102700_zps214d8a04.jpg" border="0" alt=" photo 20140514_102700_zps214d8a04.jpg"/></a>

Thanks so much for the information, and extra thanks for updating your post to include the resolution. I had the same code and the exact same symptom, and 9 years after your post, you saved me a whole ton of time and worry.

I actually had already started scoping out replacement vehicles in case the repairs were going to be too expensive, but 10 minutes later, all was good!