Master caution on bit no blink codes?

[x75thxmiltown]

My 88 951 has the "!" Master caution always on but after driving and trying to check for a fault code I got nothing. However the airbag light is on and intermittently I have my brake light come on. I was checking this due to an intermittent boost issue I have where the car seems to go into "safe" mode and only boosts at ~2 to 3 psi. Would the airbag light be setting off my master caution or am I looking at a faulty diagnostic port. By the way I confirmed the test light works by using the battery. Lastly I forgot to mention that the alarm system relay and fuse were both pulled before I bought the car also. Any input would help! Thanks

[944 Ecology]

The airbag light is setting off the ! light.

The diagnostic port does not affect the ! light.

[x75thxmiltown]

That's what I thought. I just took the car out for a quick spin, the boost fell to 3psi so I pulled over and got a 1-4 code(or a 4-1) so now I'm going to do a little research and find my boost problem. As for the airbag thanks for the info, I will be fixing that soon too

[kdjones2000]

Look in Clark's Garage for the Air Bag Reset procedure, or something close to that.

[x75thxmiltown]

Will do thanks

[x75thxmiltown]

Will a bad tps potentiometer cause low boost? I'm assuming it would due to the fact that it is tied in through the KLR.

[x75thxmiltown]

Just tested the tps at pins 22 and 23 at the KLR plug. Full closed and WOT are in spec but just before WOT is reached the resistance goes open loop then jumps to normal WOT range. I'm going to swap out the TPS and the cracked vacuum line I found while testing and see if the intermittent boost ceases to exist