socalphili

My 95 400 has decided to turn on the third gear light and not engage 4th gear/od when the lights are on. If i turn off the lights the transmission works perfectly. Fresh fluid drain and fill with type-4 and put new filter in pan. followed advice from other post to try it. Fluid was not bad, magnets where clean. Checked all the light bulbs and lighting circuit?? any ideas?? oh yeah, had a code stored for neutral saftey switch. changed switch, no more code, same issues.

LScowboyLS

the indicator to computer (range sensor part of neutral safety switch) is getting some feedback from a ground problem or short in lighting system - check wiring/grounds to rear lights and other lights

neutral safety diagnostic code was indicating the problem, but the part was fine, I predict the code will return, because the part was good in the first place - and if you paid for that part and that repair and some "mechanic" said you needed this, you need to get that money refunded, as the problem was misdiagnosed in the first place

just because the ECU gives a code for a part, doesn't mean that part is necessarily bad, it just provides a direction for your troubleshooting. OBD-II codes are a guide and a clue, they don't pinpoint the defective component, necessarily!

socalphili

Hey cowboy. Thanks for the feedback. Sort of my line of thought. I am the mechanic, so I threw the part in to verify the issue. Funny thing is I have no code back, but lost the gear indicator on the dash halfway home. The third gear light stayed on but everything else went out. Will put it in the shop tomarrow and trace down the short/ground issue. Trying to bring this one back from the dead. thought it was there until this. I have heard about the rear lights in trunk causing the "r" indicator to light, but they are all fine. Thanks.

Gene01

Is it possible that this is a symptom of the "trunk hinge wiring" problem?

LScowboyLS

it is going to likely end up being a very similar issue as the trunk hinge wiring problem, and he could check that, wouldn't hurt, but I have not heard of that being a problem any longer in the redesigned configuration on the 95 and newer models and his is a 95

LScowboyLS

by the way, from your description this is NOT going to be any kind of internal transmission problem, but a fluid and filter change is never a bad thing if done right