Tourney3p0

Hello,

I'm in the process of purchasing a 1999 Corvette coupe, and I was hoping the forum could help me out with a couple of questions I had.

First, there's something to the left of the key switch that appears to be missing. I tried looking up pictures of a C5's dash, but the steering wheel is always obstructing the location in question. It looks like the molding of the dash was made in such a way that something should be there, but it's not. Any idea what this is?

Secondly, the climate control display does not appear to work. However, all the A/C controls do appear to function. Searching through the forums lead me to a post about a possible fix for dim/dark displays. Is this the same thing, and is it common? If it's not the same thing, am I looking at dishing out big bucks for a replacement module?

Last, I'm reading conflicting information on the forum about using rear aux input on the head unit. The C5 audio thread sticky says:
"Can I add an ipod or other aux device to my stock head unit?
Yes, if you don't have a cd changer you can purchase an ipod interface from companies such as pac-audio (ipod2car)."
This doesn't really mention anything other than ipods despite the question mentioning "other aux devices". I don't really care about controlling the device through the head unit or anything like that, but I definitely do not want an FM modulator. Can you connect a device directly to the head unit using a cheap 3.5mm to RCA (I'm assuming) adapter? Some forum posts mention that this aux input is for a CD changer (which this car does not have) and will not work with any other device without a specialty adapter, while other posts seem to indicate there is no problem. This question is probably better suited for the audio section, so feel free to ignore it.

I'm a C4 guy and this will be my first C5, but hopefully these issues aren't too troubling. Otherwise the car appears to be pretty clean. I would post pictures if I could, but I'm hoping to work out these issues before the car comes into my possession.

Thanks.

Bill Curlee

There is a small plastic slotted cover and behind that cover is the interior temp sensor (small thermister) Without that sensor, the AC will not work correctly.

Before you purchase the car, read and post all the DTCs. Its important to know what DTCs are reoccuring Some mean very little but some could mean $$$$$$$$$$$

Heres how:

READING YOUR Engine Diagnostic Trouble Codes (DTC)

This procedure should be carried out any time you experience a problem with your C5. Most inexpensive store bought aftermarket code readers will ONLY read power train DTC’s. Reading the DTC’s with the C5 built in code reader will allow you to read ALL the modules in the vehicle.

The Diagnostic Display Mode is entered with the following procedure:
1) Turn on the ignition but don't start the engine.
2) Press the RESET button to turn off any warning messages. (i.e. door open, trunk open ect)
3) Press and hold the OPTIONS button
4) While holding OPTIONS, press FUEL button four times within a 10 -second period.

Initially, the on-board diagnostics go into an Automatic Mode which will cycle through each module and shows diagnostic codes in a pre-set sequence: PCM - TCS - RTD - BCM - IPC - RADIO - HVAC - LDCM - RDCM - SCM - RFA. All codes will be displayed for each module. ( i.e. PCM = 4 codes) If none are present in a given module, you will see No More Codes on the display.

There are two types of diagnostic codes, Current and History designated with a letter suffix, “C” or “H”. A current code indicates a malfunction is present in the module displaying data. A history code indicates a problem existed sometime in the last 40 or 50 ignition cycles. When not accompanied by a current code of the same number, it's potential evidence of a previous problem, now resolved, that was not removed by clearing the codes. More likely it's an indication of an intermittent malfunction.

Intermittent codes are the most challenging of the diagnostics. An intermittent code may have happened once, may have happened more than once but is inconsistent or may be happening on a regular basis but not at the time the codes are displayed. History codes can also be caused by a current malfunction in a system that is not operating at the time codes are displayed. An example is the rear window defogger which doesn't operate until the Body Control Module detects engine rpm. For history codes set by a module that does not operate with the key on and engine off, a special diagnostic tool called a Scan Tester is necessary to properly diagnose the malfunction.

Once the system has displayed all modules, it goes into the manual mode which allows selection of each module using combinations of Driver Information Center buttons. Manual mode can also be entered during the automatic sequence by pressing any button except E/M. Once the display shows Manual Diagnostics, select a module by pressing the OPTIONS button to go forward or the TRIP button to go back. Once a module is selected, a code is displayed, and if more than one are present; press GAGES to go forward or FUEL to go back.
To exit the diagnostic mode at any time, press E/M. If you want to erase codes in a given module, press RESET To reset the codes once in manual mode, press and hold RESET until it displays NO CODES Press OPTIONS to go to the next module. Repeat the steps until you have reset the codes in all the computer modules.
NOTE!! Only reset the codes IF you want to - it is NOT necessary to do this. Clearing a code does not repair a problem. You are simply erasing the evidence of it in the module's memory. If you clear the code/s, and extinguish the Check Engine Light, your emissions status ready will NOT allow you to pass an emissions test until you have completed the required driving cycles. There are a few body module DTC’s that if set will prevent the module from operating properly. Once the DTC is cleared, the module will return to full function. This is not true for power train DTCs.

If you have never read and cleared your codes, there will probably be a lot of old history DTCs. It is recommended that you clear your codes and see if any come back during a driving cycle. Those are the ones that you need to concentrate on diagnosing.

Once you have the codes, the next question is: What to do with the information?
First, consult the factory service manual. Any serious C5 Do-It-Yourself owner should invest in the Corvette Service Manual of the appropriate model year. The Service Manual is really a requirement if you want to understand and work on your C5.

NOTE and a WARNING. You can read the DTCs while the engine is running. I pull mine up all the time while driving.
WARNING. Don’t become distracted while reading DTCs while your driving and cause an accident!!!!! Use common sense and drive safe.

These are some very good C5 Diagnostic Trouble Code (DTC) explanation web sites!!! They also explain how to read the DTCs

Here are some very good sites that explain what DTC mean:

http://www.gearchatter.com/viewtopic11755.php

http://www.obd-codes.com/trouble_cod...d-ii-codes.php

Make sure to include the H or C suffix when you post your DTCs!!


The HVAC module sounds like the common resistor issue but unless you figure out if all the HVAC functions work, it difficult to know if the module id good.

Florida99

There is an interior air temp sensor left of the key. It inside the square recess. The sensor sells for about $18 and the p/n is 16267411. I believe there is a separate louvered cover over the sensor and if I'm wrong and the cover is part of the sensor, someone will correct me. If the cover is separate and I just don't remember, you'd likely be able to pick one up either here in the Parts forum or at a salvage yard but it will take some time and digging around. It's not a common item for sale but they do come up. By the way, the sensor and cover are not parts that just fall off.

Does the climate control itself work, even though the display doesn't? As you've seen, the dim display is commom and is fixable by either yourself or some forum members. There are posts on how to fix it if you search but you need some soldering skills. If someone else fixes it, will likely be under $100, more like $50. If the temp sensor is missing and the cover, I'd wonder why, what happened and and if the a/c even works. If there are more a/c problems and other parts missing, will get expensive fast. Sounds like the car wasn't maintained by someone interested in fixing common problems. Makes you wonder what else is hiding.

Tourney3p0

Thanks for the responses. I had not even considered checking past codes, though none are showing up at the moment.

I believe the air temp sensor itself is probably there and intact, but the vent that covers it is all that is missing. Since I had no frame of reference on what it might be, it just looked like a hole in the dash to me. I played with all the climate control options I could and everything seemed to work, so I'm thinking it's probably the resistors. Luckily I'm pretty confident in my soldering skills. The procedure indicates that the missing vent has to come off in order to get to the climate control module, so I'm wondering if the previous owner attempted the fix himself and accidentally broke the vent somehow. Just a guess, but I'll never know.

I changed the original post to include a (hopefully) simple audio question, but that one will probably get more responses in the audio forum. It's too bad all the generations are lumped into one on that topic.

Florida99

If it's just the grill cover that's missing, looks like it's p/n 10268306. if you search around, looks like it's around $14-15 new. good luck

search something like 'c5 corvette air temp sensor cover p/n 10268306'