My "new to me" 98 didn't have a working key fob when I purchased car. I purchased a new one...followed the instructions to match it to the car and it worked great for a few weeks. Stopped working so I checked the battery in the fob, it was fine, went through the set up again and it worked fine for a few weeks.....then it "forgot" again.....where do I go from here?

 

Is the new fob an OEM or aftermarket?

The OEM '97 to '00 have had this type of problem fairly common. Many times it can be tracked back to some bad solder on the circuit board. If you search for it on the forum, there are a few threads that describe which areas to reflow the solder to fix it.

I have a '99 which uses the same fob and had similar problems except mine would forget in a matter of a few minutes or hours. I tried the solder fixes and it didn't help mine. I finally made the upgrade to the '01 to '04 type since I needed new TPMS also. The later style seem to be more trouble free.

Good luck.

 

Do you have any MEMORY Loss issues when this happens? Sometimes a weak battery can cause this issue to happen. My 98 did it a lot until I figured out I had a very weak battery. Car still started OK but I had a LOT of memory stuff reset on me when I did a cold start.

Take a look at your DTCs and see if there are any battery related errors showing up.

BC

 

Notice the bad solder joint on Pin #1 of the chip.
That is the power to the chip!


I just bought a 1999 and the key fob was not working. Battery was dead. Replaced it was able to learn the fob to the car. Worked for a while the would not work. Could get it
to re-sync but then it would not work again. I then read about the bad solder joints on the Fob's circuit board. I brought it in to work this morning and put it under a microscope and took the picture above.................
I reflowed the solder and the Fob works fine now!


Chris

 

Have you looked for bad solder joints on the Fob's circuit board?

 

My fob is aftermarket.....what/where is the TPMS?

 

the transmitter goes defective, does your tire monitor system work correctly ????

 

What I meant by a bad battery was your 12 VDC main battery. If its weak, it can cause those symptoms. If it were me, I would have it fully tested and see if it has the correct Cold Cranking Amps..

The TPMS is inside the wheel and mounted on the rim at the valve stem.

 

Nail on the head....I get a service tire system message when I start the car. Previous owner said it started when he put run flat tires on the car.....so, guess I didn't realize the fob and the tires were connected......still not sure it's sinking in. Do I need to break the tires loose and check to see if they are still there?

 

If you have rubber coated valve stems,,,, You do NOT have sensors installed.

If you have metal valve stems with the captive nut, its a very good possibility your sensors are in place. DO They work?? Have you tried to learn them??


Bill

 

How do I "learn them....attached picture shows my stems and they sound like what you describe.

 

I've been thinking about this....the only thing that makes sense to me is that all the pieces of the system have to work for it all to work...if one section goes bad it's all bad....is this correct?

 

C5 & C6 TIRE PRESSURE SENSOR TRAINING

C5:
Reprogramming the sensors requires a strong (preferably u-shaped or circular) magnet.
1. Turn the key to the ON position but do not start the car.
2. Press the DIC RESET button to clear any warning messages, if they’re present.
3. Press the OPTIONS button and cycle through the menu until the display goes blank.
4. Press and hold the RESET button until “FOB TRAINING” appears on the display.
5. Press the OPTIONS button once. A “TIRE TRAINING” message is displayed.
6. Press the RESET button once. A “LEARN LEFT FRONT TIRE” message is displayed.
7. Hold a magnet over the Valve Stem on left front wheel. You may have to move it around the valve stem to hit the right spot.
8. When the horn beeps (about 7 seconds later), programming is complete for THAT wheel.
9. Program the other 3 wheel sensors as directed by the DIC message display. The sequence is as follows: Left Front, Right Front, Right Rear, Left Rear.
You have approximately 45 seconds to train each tire. If the sensor isn’t reset in that time, the training program shuts down and you will have to start the entire procedure over.
C6:

The C6 Corvette requires a TPMS reset tool. Excluding some very early production 2005 models, magnets will not work on the C6′s. The TPMS tool is expensive to purchase, but you may order them through a Chevrolet dealer or the Tire Rack, and most well-equipped tire shops will have the appropriate device. Instructions for use are similar to the C5:
1. Turn the key to the Accessory position but do not start the car.
2. With the key fob, press and hold the Lock and Unlock buttons simultaneously until an audible chirp is heard from the horn.
3. Hold the TPMS tool over the valve stem on left front wheel. You may have to move it around the valve stem to hit the right spot. Press the “learn” (or similar) button on the TPMS tool.
4. When the horn beeps (about 3 seconds later), programming is complete for THAT wheel.
5. Repeat steps 3 and 4 for the other 3 wheels. The sequence is as follows: Left Front, Right Front, Right Rear, Left Rear.
After resetting the left rear wheel, an audible double-chirp is heard from the horn. This completes the sequence.
CORVETTE CENTRAL TPS INFO:
http://www.corvetteonline.com/tech-s...nitor-sensors/

 

OK, took a try this morning....used two magnets (fairly strong that I use when welding) and never could get the front left tire to "beep" or learn.....must be something else wrong. I tried different positions around the stem but nothing worked. Thanks for your help...any more ideas?

 

This morning I went through the full drill....a friend of mine has the reset tool at his tire shop. We used both his tool and a circular magnet and nothing worked. His tool showed that the tire monitor units were working so I guess my PCM/VCM is bad.

Should I replace it with another '98 unit or upgrade to a newer unit? I have seen in some posts where the newer units are better. Also, would I need to upgrade my tire units and FOB if I upgrade the PCM/VCM unit?

 

I replaced my whole system with https://www.corvetteforum.com/forums...rformance.html //// my key fob's worked for 3 days max, and my tire system never (1999) it was a little less money then (2014) and I did not want to spend that much !!! My key fob's looked like they went though the war and they are around 70 bucks each, after all said and done it was well worth the cost (to me) and now don't even think about it///// because it all works as new

 

Your PCM IS NOT the problem! The TIRE PRESSURE MONITOR SYSTEM consists of the tire pressure sensor, the Remote Function Actuator and the BCM

The BCM gets the TPMS & FOB interface signals from the RFA and process those signals to make the rest of the car do what its suppose to do.

IF, your FOBs work, the RFA is most likely working properly:



The RFA connects to the BCM through the SERIAL DATA LINE (DATA LINK CONNECTOR)

 

USING a TPM Interface ( reset tool ) unit will NOT program our TPMS (if they are C5 OEM) The ONLY WAY to wake them up is using a magnet. The magnet picks up a reed switch inside the sensor and causes the sensor to turn on. Centrifugal force is what turns on the sensor when the car is moving.

I set the magnet just inboard of the stem on the rim where it sits inside the rim.

When you enter the TPMS Training in the DIC, what do you see for training messages?

Bill

 

The system worked just like the detail in the earlier post....I got to "learn left front" and nothing happened. We put the circular magnet that was in his reset kit around the valve stem. We tried everything we could think off and yes my FOB works...has been for several days but I know it won't last. He even tried to let some air out while "learning" as that sometimes helps the process in his experience.