I have a 95 4runner with a 99 3.4 and am getting a P1780 trans control switch (O/D cancel) out of self test, code. Any idea on what I need to do to fix this?
Thanks

 

P1780
(DI–261)
Park/Neutral Position Switch Malfunction (Only for A/T)

Short in park/neutral position switch circuit

Park/neutral position switch

ECM

2 or more switches are ON simultaneously for N, 2, L and R position (2 trip detection logic)
P1780
When driving under conditions (a) and (b) for 30 sec. or more
the park/neutral position switch is ON (N position):
(2 trip detection logic)
(a) Vehicle speed: 70 km/h (44 mph) or more
(b) Engine speed: 1,500 – 2,500 rpm

Short in park/neutral position switch circuit

Park/neutral position switch

ECM

 

Is there anyway to bypass the switches in order to pass smog for now? If the tach is not working could it cause this code to come up?

 

What you see listed above is from a factory service manual. So, if it's not listed, then Toyota doesn't think it will cause this problem.

It's not as easy as "bypassing switches" since there is position detection logic run over multiple trips.

Just fix it. The switch is probably just out of adjustment.

 

Thanks for the reply. I tried adjusting the switch on the tranny and checked the switch on the shifter, no luck. The strange thing is the light will not come on till you have started the car and put it in gear and then turned it off and restarted it and put it in gear a second time.

 

That's the multiple trip detection logic we were talking about it. Believe it or not, Toyota doesn't want to bother you with "Check Engine" or "Malfunction Indicator" lights unless they have a good reason to do so. So, many of the OBDII systems require more than one "trip" with a failure to light the lamp. On this one, it requires that the failure be detected twice under certain prescribed conditions.

Here's the diagnostics page from my rig if you want to dig into it more. I suspect the diagnosis section would be similar for yours, even if the wiring diagram is not.

http://www.watrd.com/work/cip1780.pdf