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1985 Vette. Code 32. I have new EGR valve, new temp sensor and new solenoid. But, after driving for about 30 minutes, code 32 appears. Vacuum lines are good. What am I missing?
Could also be an open circuit on the thermal switch circuit, even if there is flow. A closed switch should fail right away at startup. As a test, you could clear codes, then ground the switch and see if the code 32 returns again right after startup to at least verify circuit integrity between the switch and the ecm.
Not exactly sure where the switch is located on an 85 with iron heads since there is no external feed tube like the aluminum head cars, but I presume its near the back of the intake. If you've already replaced it then you know where it is.
I am no expert, so forgive me, just trying to help. Failure is obviously the ECM not recieiving the open signal when commanded at cruise so no problems with valve position at startup. Is code 32 the reason for new parts? I checked the 1987 PN against the 85 and they are different. How did you test the vacuum lines ?
What part # is your new EGR valve, do you have a manual or automatic? SCHEMATIC is for 87
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Last edited by Vets-Vet; Dec 19, 2022 at 12:50 PM.
Thanks for the replies. I must also add that when I replaced the mentioned components, I cleaned the throttle body as well as the EGR passages in the intake plenum being that I had those removed.. One of those passage was clogged, but I cleaned it (and the other) thoroughly. The Code 32 sems to only appear when doing highway driving. When driving around in town, I have not gotten the code. Again, thanks for the excellent replies. I am beginning to think that the egr Solenoid might not be good. Hmmm.
Yes, the parts were replaced because of the Code 32. The EGR valve is the proper item ... for an automatic transmission. The egr solenoid is listed as being for 1985-90 (I think). It mounts differently and I had to make a bracket for it to be mounted in the proper location. The connections, electrical and vacuum, are the same as the original (which I no longer have). It just might be that this is the issue.
The new solenoid did not test well (vacuum) so I put the old solenoid back on. It tested well. And, I do know that I am getting proper voltage to the component. I only replace it because I was changing out everything as well as cleaning out the passages. So, I will drive it with the old solenoid on and see what happens. I have a 1-hour road trip on Wednesday. I will post the results after the trip
FYI and for further clarification, I was getting the code a few months ago and I thought it might be the temp sensos, so I just changed out all of the egr components (egr valve, temp sensor and solenoid) while I was doing that.
I am making a road trip tomorrow (Wednesday) and I will post the results. But, I removed the new solenoid and put the old one back on. The new solenoid did not hold a vacuum as I thought it was supposed to (the old one did). Now I am not sure where my original issue came from. The new Solenoid was purchased from Mid-America. It was obviously for the 86 -90 model years since it mounted differently from the original. I had to make a bracket for it to be mounted on the engine as the original one was. I have not seen any new Solenoid (or temp sensor) listed for the 85 model year.
""There were distinct differences in the way GM handled control of the EGR valve. Additionally, they used two different ways to determine if the exhaust gas flowed. All C4s used electric solenoids, some NO (normally open) or NC (normally closed) until current was supplied. Some used manifold vacuum like the 1984 and 1992-1996 Corvette opening the EGR valve with a NC solenoid. The 1985-1989 Corvettes used ported vacuum supplying vacuum once the throttle was opened through a NO vacuum control valve solenoid.""
Went on a road trip today. SES light came back on after about 10 minutes of highway driving.. I am beginning to think that the new temp switch is the issue. The temp switch for the 85 model is not to be found. Someone on this forum stated that the switch for the 86 model is the same except for the length of the connecting wire. That person said to splice in more wire to make it the proper length and all will be well. I did that. I bought the switch listed for the 86 - ??, added the necessary wire and installed it. Maybe that advice was not correct. Maybe the switch for the 86 is different in other ways. The car runs great. Gas mileage is excellent, coolant temp is great as well as everything else. I'll keep probing. The SES light is just an annoyance since the car is running good otherwise.
Thanks. I will get back to this real soon. I have to work outside and it is COLD here today and forecasted the same for the next few days. I have checked some of what you suggested and all seemed to be ok. The egr valve is new, but of course that doesn't mean it is functioning properly. I am beginning to think that there is a flow issue caused by a (some) clogged passage(s). Anyway, when the weather gets back warmer, I will get back to this project. I have read where some "fool" the computer into thinking all is well by placing a diode in the temp sensor power line. (This is done when egr is deleted). Does anyone know what value (impedance/resistance) diode is used?
FYI Update on the code 32 issue. I did a bit more EGR passage cleaning and so far no code 32. I have not driven any long distances, but I have driven several times about 30 miles steady on the highway and have not gotten the code. Just an update. Soon I will be doing a bit more extended distance driving.
Code 32
