Intermittents, electrical ?

[ChrisWhewell]

I ran across this, and thought I'd share:   #93-8A-110: INTERMITTENT CODES E047,B333 B334,B335,B336 AND/OR ...

 

I have a intermittent code 334 that makes my tachometer and temperature gauge go on and off.   Trouble is, the AC clutch is somehow involved, when the tach display disappears, it makes the AC compressor turn off.   Then, bingo, back on again.   Pain in the neck.   I was thinking of swapping the ECM but sense the issue is in a connecting wire between unknown x and unknown y.   Kid is going off to school next week and I've been throwing $$ at my Reatta but for now am too cheap to buy the expensive FSM for the 90 Reatta.   If its not too much to ask, can someone maybe post the diagnostic tree for b334 ?   I'd also like to know where the pins on the back of the instrument cluster go to, if the FSM has a diagram identifying what each pin is for.

 

In the link above, it mentions on page 2 near the bottom in paragraph 1. that there's a ground "on the block near the starter solenoid"  Ronnie, maybe add that to your ROJ topic on the grounds ?

 

  

 

I've had this one happen also..... :  "ECC switches to full heat at high blower speed out the front defrost ducts" 

 

 

 

Edited August 12, 2016 by ChrisWhewell (see edit history)

[ChrisWhewell]

FIXED.   The problem was the ECM.   I pulled the ECM from my parts car, it has a sticker on it that says "GM Remanufactured", so obviously someone swapped it already on that car.  Popped it into the '90 I like more, and voila.   No more intermittent tach and temp gauge problem and the AC works fine.  (lack of temp gauge was making AC clutch de-energize).  Also, was previously unable to read any engine data when in diagnostic mode, so that's fixed also.  Now to hit the highway, I bet the cruise control will also work, lets find out...

[KDirk]

Ah, the dividends paid by a parts car. Glad to see you got it fixed, and easily too. I am looking at another parts car presently, a 90 white and blue coupe. Has enough usable stuff on it to justify the purchase price but won't be able to pick it up for a week. This will be the fourth parts car I've bought and the third to be dismantled (one is going to be a winter beater and get parted come spring) besides two that I helped Dave part out. I think this going to be it, no more parts cars for a while.

 

Anyway, this is another example of a bad ECM doing all kinds of unpredictable stuff. Much like a bad ICM, the symptoms can be all over the place. Been there and done that myself.

 

[ChrisWhewell]

Yep.  And the trunk quit opening itself and door locks stopped actuating themselves on startup also, after ECM change. Don't ask.... but, my radio used to not put out sound until like 5 minutes after I'd turn it on, but now comes on instantly.  So yeah, depending on how its screwed up, a bad ECM can make some strange things happen !!