luvchevys

. I have a 2004 cavalier 2.2 eco I just bought 2 weeks ago for my 93 yr old gramother that still drives car has 67k low miles . when I bought it the engine light was out . I hauled it home an did brakes an struts ect , to make it safe for the raod , on my test drive I noticed the light was on so I came back home an scaned it ,code that came up p1810 tfp switch valve I replaced that which was not fun, an back together new fluid , 1st ride it was fine shift great all gears 1234 lock up . shut it off went to restart light back on took it for a ride only had 123 gare no 4th or lock up . pulled battery cable off for 5 min light was out went for a ride shifted fine all 4 gears an lock up . shut off light back on same thing again 123 no 4th or lock up .. scaned the car an a new code along with the old one came up --p1810 an p1815 which is shift range selctor out of range. called the gm dealer an they told me that there is a pressure plate that is on the valve body that may be the cause !! ok 2nd time tear down relaced the pressure plate an the tfp valve again checked all conections an plugs while I had the cover off all looked good . back together road test ..... no diffrent. than before first run out was fine all gears . shut off restart limp mode no forth gear . pull battery cable off 5 min an try again fine . ... it only does it on the 2nd restart that it throws the code ..any ideas or help would be great .. an sorry I wrote so much just at my witts end with this car !!!

luvchevys

would low or overfill transmission fluid cause this problem ?

EinST

Welcome to the forum. It sounds like you have a wiring problem on the TFP switch circuits, i.e., a short to ground, open, or short to voltage. A short to voltage is rare and thus you can concentrate on the first two. It would be easier if you had a scan tool that can read out the voltage states on the individual circuits. Anyway, check the wiring:

Terminal N, PNK wire, Trans Range-A to PCM Connector C2, Terminal 55
Terminal R, DK BLU wire, Trans Range-B to PCM Connector C2, Terminal 56
Terminal P, RED wire, Trans Range-C to PCM Connector C2, Terminal 57

Internally they are wired up like:

Terminal N, PNK wire, Trans Range-A to TFP Switch Terminal A
Terminal R, DK BLU wire, Trans Range-B to TFP Switch Terminal B
Terminal P, ORG wire, Trans Range-C to TFP Switch Terminal C

luvchevys

whats a good scan tool to use to check voltage ? Have you ever heard of this happning before .

EinST

A scan tool will read out the switch states. A Tech 2 or a professional scan tool costing thousands would do it. You obviously can get by with a multimeter and a little luck to track down a wiring problem. Just keep in mind that the PCM supplies ignition voltage on each circuit which the corresponding TFP switch grounds or not to indicate close/open states. As for the particular trouble codes, I've never personally come across them.

luvchevys

Thanks for the info I found a garage in my area that has a scanner that will read voltage on the diffrent switches an i'm going there tomorrow . are there any wiring scamatics available on this car ? that would be helpfull . Thanks

EinST

See my post #3 above for wiring from the point of view of the 14-conductor wiring harness at the transaxle. The shop should have access to the diagnostic procedures and more. Hope it works out for you.

luvchevys

made it to the shop today ran a scan an all circuts working properly ? just finshed an oms test found 001 resistance on all three colors . going to redo some grounds an check the wires in the loom from the pcm to the plug .. not sure what to do next any aditional grounds that would cause this that I may be missing ? or could it be possible to be an internal issue with the trans .

EinST

That's too bad, then. The diagnostic procedures should have called out for something along the line of "start the engine and then move the shifter to each transmission range, P-D1, while verifying the correct TFP switch states." The problem was probably there even if the malfunction indicator weren't lit (P1810 will only be set during during the second consecutive trip).

luvchevys

had a freind of mine check the car out tonight an all the wires tested good , what he did find is the pcm has 12 volts coming out of it ? he wasn't sure of the correct voltage for this car but said it should be around 5 volts , said that the solnoids an switch's don't require that much an that maybe the reason for it trowing a code . could it be a bad pcm ??