[AirAJ]

I have a 97 saab 900 se 2.0 turbo. 150K

Last fall the check engine / Check gear box lights came on and my saab was stuck in Limp mode. This happened off and on all winter. I never could find a pattern of when it would work or fail. However, when I stopped using the alarm system over the summer the car ran great.

Here is a short description of the issue.

About this time last year the tranny went into limp mode. After searching the forums I replaced the NPS (neutral position or safety Switch), but had no change.
I Replaced Battery with no change
Flushed the Trans with no change

In May the alarm system would not turn off with the Fob. After 30 minutes of trying it i was finally able to disable the alarm. Not trusting the Fob anymore I stopped setting the alarm (just locked the doors with the Key). As soon I stopped using the alarm the check gear box light went out and everything worked Fine for about 6 months. Until this October. Now the Check gear box light is back on.

To me it appears to be an electrical issue. Wondering if it could be related to the weather since it appears to run better in warm weather. Maybe a ground wire or a harness that contracts as the weather gets down closer to freezing. Just looking for some hints on where to look for electrical issues that could cause the vehicle to go into limp mode. Below is a list of other strange issues that happen when the check gearbox light is on (which is why I suspect electrical) Plus the fact that the transmission shifts perfectly when the light is not illuminated.


Other current issues:

1. Head lights - could be headlight relay issue??
Headlights turn off when switch is set to ON - unless Check Gear light is off (then the head lights are always on)
Headlights turn on when switch is set to Off - always

2. While check gear box light is illuminated (system in limp mode) the Radio will turn itself on and off randomly. (this does not happen when shifting normally)

3. Trouble disabling Alarm system (new FOB batteries make no difference)

Any help is appreciated.

 

[EdT]

Other current issues:

1. Head lights - could be headlight relay issue??
Headlights turn off when switch is set to ON - unless Check Gear light is off (then the head lights are always on)
Headlights turn on when switch is set to Off - always

Unless you've turned off DRLs (Tech II plus fuse), the headlights will be on when the car is on, no matter where the headlight switch is turned. With the key turned to lock (or out of the car), the headlights will not be on, although the parking lights can be on if the switch is in the middle position.

If the key is turned to OFF, the headlights are on if in the left position, off in the right, and parking lights in the middle.

If the key is ON, headlights are on in all switch positions. Foglights and high beams won't work unless switch in leftmost position.

What do your lights do that's different from what I described?

2. While check gear box light is illuminated (system in limp mode) the Radio will turn itself on and off randomly. (this does not happen when shifting normally)

3. Trouble disabling Alarm system (new FOB batteries make no difference)

Any help is appreciated.

Have the transmission codes been read?

There is one ground wire that's supposed to go to the engine block, and I expect another ground strap that runs between body and transmission just visible in the left wheel well ahead of the wheel. I would check all those grounds, plus the ones by the ECU. Intermittent electrical glitches are no fun to find.

 

[AirAJ]

Code for check gear box

Checked the codes and it came back with p0705 -neutral safety switch

sorry I was confusing explains the lights. They work as you explained until the check engine/ check gear box lights come on. Once those error lights are on, the head lights turn off whenever the headlight switch is turned on (radio also turns off) and they turn back on when the headlight switch is turned off. The radio also stays on after the keys are removed from the ignition. As soon as I clear the error code things all work normally until the code comes back. Thanks for any help.

AJ

 

[EdT]

Checked the codes and it came back with p0705 -neutral safety switch

sorry I was confusing explains the lights. They work as you explained until the check engine/ check gear box lights come on. Once those error lights are on, the head lights turn off whenever the headlight switch is turned on (radio also turns off) and they turn back on when the headlight switch is turned off. The radio also stays on after the keys are removed from the ignition. As soon as I clear the error code things all work normally until the code comes back. Thanks for any help.

AJ

That is bizarre. I don't have an automatic, nor these kinds of electrical problems, so I can't really comment. Honestly, it sounds like an issue that someone familiar with the logic behind Saab's electrical system may be able to diagnose. A Tech II used by a competent tech may be the place to start.

 

[jakejm79]

Checked the codes and it came back with p0705 -neutral safety switch

sorry I was confusing explains the lights. They work as you explained until the check engine/ check gear box lights come on. Once those error lights are on, the head lights turn off whenever the headlight switch is turned on (radio also turns off) and they turn back on when the headlight switch is turned off. The radio also stays on after the keys are removed from the ignition. As soon as I clear the error code things all work normally until the code comes back. Thanks for any help.

AJ

It could be an issue with the ignition switch, on the ng900 the one of the circuits for the headlights is also shared by the acc source for the radio.

 

[AirAJ]

check engine - check gear box

Noticed one more thing today. If I drive the car long enough to warm it up really well (over 10 miles) and then shut it off and start it back up again it shifts fine. Once the car cools the error lights come on and it is back into limp mode. Tonight I am testing the headlight relay... Could be that the lights etc are not related but just a coincidence so if that is failing want to fix it to rule it out. Will also check wiring around the under hood fuse panel for shorts and clean up all grounds.