I just recently purchased a "solid" 2 owner, 1999 C5 with only 47,000mi. Went to dealership and looked it over then took it out for a test ride. It seemed to crank for quite a while before starting. Sometimes it starts right up, other times it doesn't. If it doesn't start within two seconds, I release the key and try it again with a high success rate. Test ride went good except the air wasn't working properly. They brought it into the shop and look at the blend door actuator which checked out good. Battery came out in order to change a vacuum leak for the blend door? Battery went back in and everything appeared to work as it should. Drove it 250 miles home with no issues. Shut car off and let sit for around half hour. start it up and now the active handling warming up message comes on every time I start the car and doesn't go out for quite some time. Not typical from the research I have done. Pulled the codes when I got back to my shop and my head started spinning.
10PCM
p0113 c
p1111 hc

28-TCS
c1255 h

58-SDM
b1001 h

A0-LDCM
b2282 h
b2284 h
u1064 h

B0 RFA
u1096 h
u1064 h
u1016 h

A6 SCM
b2860 h

A1 RDCM
b2253 h
b2283 h
b2285 h
u1064 h
u1096 h
I will admit that before last Sunday, I didn't know anything about these cars. Spur of the moment purchase. Really hoping someone can give me some insight before I regret my purchase even more.

 

Congrats on your purchase !!...All but one...the P0113 are “history” codes...P0113 is a IAT “circuit high” issue...now you said you brought the car to your “shop”...what kind of shop...automotive, body shop ??...if neither do you own a DVOM ??...IAT is a simple 2 wire thermistor so it’s basically a 5 volt reference voltage and sensor ground...if you have a DVOM and would like to know how to diagnose it let me know !!

 

C5 Diag, you are honestly speaking french to me haha. The auto dealer I purchased the car from were also the ones that did the work. I sure as hell wasn't driving 4 hours with iffy AC in 92* weather. I disconnected the negative terminal when I parked it earlier today. I was thinking I could go through and do the whole BCM relearn and clear up some issues. The hard starting and continuous advance control warm up is bothering me

 

And I am a little slow today. Yes I have a DVOM.

 

The IAT sensor if bad can cause those starting issues plus the active handling warm up !!...let’s do this test...disconnect the IAT sensor and with key ON see if you have 5 volts on the TAN wire I believe...if good voltage plug the sensor back in and get a safety pin and from the back of the connector probe the PURPLE wire from the back side...


there should be a little gap...we call this “back probing”...this is the sensor ground...if you see 0 volts you have an open in the sensor...replace it but with an OEM one !!

 

I just got back from my shop. I unplugged the sensor and checked current on the mating side. Neg to purple and Pos to tan. Showed 5 volts. Plugged back in and chased down a back-probe kit. I've never back-probed so am unclear as to what you are touching pos/neg probes to? Thank you very much by the way! Jumped head first into the Corvette world.

 

If you connected the DVOM between the 2 wires and are reading 5 volts the wiring is good !!...to verify 100 % that the IAT sensor is bad remove it and connect the DVOM between the 2 IAT sensor pins and select OHMS...get a hair dryer or heat gun and heat the sensor...you should see the resistance decrease...if not the IAT sensor is bad!!

 

I must have missed the p1111 HC...it’s really a P0113...IAT “range/performance” that is also a “current” DTC....and if you watched the video DON’T change a part solely based on what the DTC says...you’ll be wasting a lot of money !!

 

Update: I pulled the AIT plug and confirmed 5 volts coming through the plug. Deleted all codes last night and went for a drive. High voltage codes came back. Pulled the sensor this morning to test. Checked out good, reinstalled, cleared codes and went for a drive. No codes present now after start stop half dozen times. Kind of at a loss. I'll probably throw a new one in due to the fact that the car is 20 years old. Only code I have been throwing now has been for the telescoping wheel.

 

Since you tested the sensor and it’s good it’s more than likely just a bad connection...I’d connect the voltmeter and start shaking down the wiring...most likely it’s right where the harness plugs in is where it may be faulty !!

 

Well, since I broke off the tang that keeps the two connected, I will be throwing in a new sensor and will look for the part number for the pigtail. What bothers me is all of the PCM codes I was getting. Did the dealership not delete them? Was it because the battery was taken out then put back in? No clue. As for the starting, something is still wonky there.