OK here is what's going on,

Car has been great for years on end, Still runs & shifts great untill it acts up.
(randomly)

First notice it will shift up and down at will & search for gears, Converter locks in and out & motor runs bad with very little power.

First thoughts was speed sensor or trans issue so I checked for codes.
with exception on the O2 sensor I am getting codes for every sensor in the car.
Also coil & P/N switch.

Replaced the air intake & coolant sensors then coil. cleared codes ran it 2 days and it all came back. (including codes for the new sensors that were replaced)

So one mentioned the input sensor could be to blame as if the pcm didn't know what the motor was doing or how fast/slow it was running it would mess everything else up. (just replaced that too)

Cleared codes and I'm back to square one.

Removed and cleaned every ground I could find under the hood and the strap to engine, Also ran another ground from engine to battery. (results are the same) Alternator tested and ok, battery load tested and ok.

Odd codes I get are
no power or low voltage to pin #5 at pcm (which was the input speed sensor & just replaced)

other odd codes, intermittent (something or other) with P/N switch
and open circuit at P/N switch ...

Any ideas?
Could the Park/Neutral switch cause this or would I just be chasing another gremlin?

Any & all help would be greatly appreciated ...................................... Sinc. Joe


want to ad,
This will only happen after the engine is at FOT (full operating temp)
Makes a little bit of sense as I'll guess it's when it comes out of "open loop"
&
the speedometer works at all speeds and the ABS light is not on................ Thanks again

 

The possibility of a defective trans range switch (formally park neutral switch) is good.
The resistors inside the switch tell the trans system what range to be in and if the signals are incorrect the trans and system hunt, go into wrong gears, some not at all, all kinds of crazy problems. The resistance readings are very important and the slightest poor connection can give all kinds of problems. Suggest replacing the switch.

 

Hank is there anyway to test that switch? (ohms, voltmeter)
I just hate the thought of throwing more money and the problem comes back.

 

Well I replaced the P/N switch and it's still the same, Does anyone have any ideas at all? I would really appreciate any and all help. .. Thanks Joe

 

I should have read your original post more carefully.
When we get a mess of codes it usually indicates a voltage loss somewhere.
I believe you checked ALL the ground connections, what about the positive side connections right from the battery through the fuse box and fuse connections?

 

ok
Nope I didn't check the + wires but I'll make that the next thing.

Can't remember if I said it but also got a code says alt. is over charging, Took that and had it tested 3 times and it checked out good.

I tell ya Hank this is eating away at me, It's a good running car & up untill this it has been extremely dependable.

 

One reason the alt will overcharge is a poor connection in the supply system since the regulator is sensing a lower voltage and telling the alt to increase the charge rate to bring the system up to 14 volts.

 

Got started on the other wires today
made it from battery to power dist. box. so far
Wires were a bit cruded, Wire brush on the dremel and cleaned them all.
(still no luck) will continue on from there..

 

Hello again Hank,
Some more questions for you,

Could the pcm cause this?
(My train of thought if the pcm is or going bad car wouldn't start or stall out)

Is there a relay for the pcm?

What supplies power to the pcm?

I'm just thinking were it is intermittent maybe not a wire issue but something faulty and shutting down when it gets hot. (what do you think?)

Very grateful for all your help, ..........Joe

 

What are the latest codes you received?