OBD 1 Dianogistics Code 32 For GM Vechiles 1991 GMC Sonoma

Sorry ,Long Post !

I have a 1991 GMC S-15 Snoma Pickup with a 2.5 4 Tech. engine and a 5 speed transmission . No air conditioning . The check engine light has been comming on and going off intermitently over the last couple of years . I finally bought a Actron OBD1 Code Scanner from Autozone ( the kind that makes the check engine light flash ) . See my post on Tool Talk about the testers . I tested the truck with it today and got a code 32 which, according to the book that came with the tester ,code 32 means :

Barometric pressure (BARO ) sensor circuit failure

OR

Exhaust gas recirculation ( EGR ) valve diagnostic switch - closed during engine start up or open when EGR flow requested by ECM

OR

EGR/EVRV

I don't remember these trucks ( especially these model years ) having a BARO circuit . Do they ? Also, is there anyway to test the EGR valve without just putting a new one on it and hoping that it fixes it ? Was there a problem with these valves on these model trucks ? The motor is not the original motor , but just like it . Maybe a yer or two difference , but the problem did start until a couple years later also the truck has been wrecked and rebuilt ( new frame and doghouse ) and the problem started about a year or two later . The motor dosen't act up when the light comes on . It keeps on running fine. If I'm not mistaken the EGR valve runs by vacuumn .

P.S. The book defined the light comming on and going off as an intermittent problem meaning that the computer saw a problem ,but it went away and the code stayed in the computers memory.

What is all of your thoughts on this ?

Thank you for any and all help .

Whizkid

Some GM vehicles use the MAP sensor as a baro sensor as the key is turned on but but before startup to read the current barometric pressure.

The '94 turbodiesel pickup I'm working with now has ONE sensor... baro BEFORE startup, then EGR apply vacuum AFTER startup. I know some gassers are set up that way, as well.

As a cheap diagnostic test you might try "T"ing a vacuum gauge into the EGR apply line and see if it has vacuum when the EGR would be applied, typically at crusing speeds.

Chevies have numerous wiring harness problems. Next time the light comes on, grab the wiring harness, at the firewall, behind the motor, and twist it and yank it a little, and see if the light goes out. Also, check your vacuum hoses, for leaks and brittleness.

code 32 means you have something wrong with the egr system -- and yes there are test u can do , need a vacum pump , my haynes book tells how to ,need to get a book and go from there

The best way to turn off a check engine light is to have the PCM do it. Intermittent faults can indicate sensor issues as well as wiring issues. Flow chart diagnostics are the best way of narrowing down the problem. Do you have any driveability issues with the truck or do you have codes w/o driveability issues? Have any repairs been done to the truck recently? Hope this helps. Gerard

ASEguy,

No , I do not have any driveability issuse with the truck . When the light comes on nothing changes with the running of the motor or with the driving. It runs the same with the light on as it does with the light off. No repairs of any kind have been done other than oil changes , but it was doing this before as well as after the oil changes. I should mention that the truck does a lot of sitting , especially during the winter . I log about 500 - 2500 miles average a year on it , give or take depending on how much I need the truck or I get in the mood to drive it instead of my car . But , I log about 10,000 -15,000 or more a year on my car .

Thanks ,
Whizkid

That engine uses the MAP sensor reading before startup to determine BARO value. If memory serves, the EGR valve is not computer controlled. It uses ported vacuum from the base of the TBI unit. Check for leaking or plugged vacuum line to the EGR valve AND to the MAP sensor. While you're at it, check for vacuum leaks at all the vacuum fittings. The electrical connector at the MAP sensor often gets the retainer tab broken off, so check to be sure it's not loose. A "chicken band" plastic tie is a common fix for that problem. Also, you might want to remove the EGR valve and check for a plugged passage in the intake manifold. HTH
Good Luck and God Bless

With fuel injection your code is egr related not baro related unless you have a carburated engine. As stated previously you need to obtain a manual and test according to the flowchart for that code.

google : GM code 32 test charts" learn how the system works first...

http://repairpal.com/gm-obd-I-code-chart

read read read,,, that's were most of us started... Bob and ASE guy know their stuff,,, the problem with the internet is getting miss lead you have to chiffer thru the mess... lots of good info if you go to the right places,,, Some good forums some full of B.S.







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