It’s been a really bad year for my ’91. Dead short wiped out ECM & CCM. Removed every wire in the car before finding the bare wires behind the right head (against the bellhousing). Then found the new GM CCM was bad. Side tank of the radiator cracked (on course during AX run), new upper ball joints went bad, heater core blew a seam, auto trans went south just before Christmas. Dec 29, heading out of town for 29th anniversary and New Years, 5 minutes up the freeway and I get a SES. Checked the codes when we got home - 1.= H72; 4.= C32. EGR fault.
I checked the diaphragm (holds vacuum), replaced the tube from the solenoid to the valve, checked ohms on the solenoid (28.4 - anything over 20.0 is supposed to be ok), the 91 doesn't have a EGR temp sensor (which eliminates one potential problem), test light to solenoid harness and - whoops - a challenge. According to the book - ground test light, probe each wire with the key on, engine off, test light should light up on each wire. The pink wire lights up (from the fuse box) the grey one doesn't (from the ECM). The wire from ECM grey connector to EGR solenoid is good. Indicating the ECM is not working??? Or did I read it all wrong. Should the grey wire only light up when in closed loop?
Any help trying to understand all this would be appreciated.
T. I. A.
Subman

I am surprised that the test flow chart doesn't say what to do when a wire doesn't respond as expected.

Any other thoughts?

Kinda strange, but the FSM sheets I have must be for an earlier model(s). It keeps referring to the EGR temp switch, which to 91 doesn’t have.
I also have a sheet I copied from the “other” forum that refers to placing a diode between the temp switch and the grey wire to the EGR solenoid.
So I went to the “other book” (Haynes) -

“#20 - Ignition on, engine off, ground ALDL, apply 10” vacuum to the manifold side of the EGR solenoid. If it holds, proceed to #24
#24 – Unground ALDL and vacuum should drop
#25 – If no drop in vacuum, disconnect the solenoid harness. If vacuum drops, repair short to ground in circuit 435. If no short, ECM is faulty NOTE:Before replacing the ECM check the resistance of each ECM controlled relay and solenoid . . . . . . . . Replace any relay or solenoid that has 20 ohms or less resistance
If there is no drop in vacuum, replace the EGR solenoid.

At that point it was late and I stopped trying to figure it out. However, copying the above, I noticed there is an additional test involving vacuum, starting the engine, run at 1500 rpm in park, then in drive, test lights etc.
I’ll try that tomorrow. If that passes muster, I’m back to a faulty ECM, I think.
Will post findings as soon as I can figure out what I’m supposed to find.
Subman

UPDATE - Started from the beginning this morning on all the tests and found I had neglected to turn the key on when checking the vacuum test through the solenoid.
Vacuum dropped. Tested the ECM and it did what it was supposed to. . . . diagnoses – EGR vacuum solenoid is toast. Now the challenge is finding one. I checked AZ, Kragens, NAPA, Pep Boys, local Chevy dealer, local independents and J&D Corvette to try to pick one up today. Prices ranged from 55.00 – 125.00. And nobody has one in stock - I think that it’s Borg-Warner that no longer makes the part.
I can feel the Corvette tax coming. I don’t mind a bit of taxing, but when I don’t even get kissed - - -
Subman

Call Chris May at Superior Chevy on Monday morning first thing.

1.800.728.8267

Chris is THE man...

The ACDelco # is 214-340. The GM number is 1997195, from what I can figure.

Looks like that part may be hard to find:

http://www.automotiveforums.com/vbulletin/t707804.html

More bad news...

http://corvettemechanic.com/forum/showthread.php?p=7100

Klaus - Thanks (I think) for the info and update. I found 2 independant auto parts stores that SAY they can get it on Monday. Hopefully, between those 2 and Chris May, somebody has something. BTW, I have been trying to get this car smogged since May. It failed twice because for N0x (this solenoid has probably been the cause) and since then every time I have the time to get it to the test station, something else broke. The SES light doesn't get a chance to activate since the drive to work is surface streets and I have not taken a non-stop and go ride on the freeway in a year.
Subman

I purchased one from that national auction site...the seller was"thepartsladi". I think it was around $50.00 and was advertised as AC Delco. :thumbleft:

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good luck!!! Get it passed... then SELL IT!!!!! Before something else breaks...

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Am I confused... I thought she was a scammer? Or is that someone else?

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NOT a scammer..... they have over 20932 transactions with 100% Positive.