1999 vette w/ something wrong with the RFA module.

It has the following codes:

U1096 - no comm to IPC
U1064 - no comm to BCM
U1016 - no comm to PCM

here's a little background info. If i unplug the RFA, replug it back in, reprogram the FOBs - all is well. FOBs open close doors, pop trunk, ect. But, if i let the car sit (now i haven't moved it at all), and come back like 5 minutes later. The fobs don't do anything again, unless I unplug the RFA and repeat the process.

I've opened up the RFA... eveyrthing is clean and looks new. I even cleaned it with some alcohol and a toothbrush just for the hell of it. I've checked all my grounds on my car, checked voltage at the RFA. Everything should work. But for whatever reason, after a bit of time, it seems to timeout or lose communication.

Tire pressure sensors work fine, with exception to front drivers side (the battery is dying, so it doesn't come up till a drive for couple mins).

So has anyone experienced anything like this? Or have any ideas why it would work fine, then stop working?

I'd replace it, if I knew that was the problem. If I do replace it, could I use a later model RFA, buy the matching TPS's and a new set of FOBs?

 

 

Have you tried new batt's in the fobs?
Do you have a friend you can borrow a fob from? Odd that both fobs would go bad at the same time, but I would lean towards a bad fob(s), especially if your TPMs are working. If you can borrow one and see if it will hold the program, that would be a free and easy way to troubleshoot the RFA receiver.
Here's a current thread you might want to follow on upgrading to the late model RFA.
http://forums.corvetteforum.com/show....php?t=2073165

 

Yep, I tried new batteries in the fobs. I don't think it's fob related, i think it's the receiver end. If my fobs didn't work, and there was no issue with the RFA, then in theory there shouldn't be RFA codes present, cause it wouldn't know something (the fob) was trying to communicate with it (the rfa). Unless I am thinking this through wrong?

This is how I would think the system communicates (just my logical guess):

FOB (press unlock/lock button) -> RFA (receives the signal from FOB) -> BCM (receives command from RFA - Unlocks/locks doors) -> IPC (displays info on instrument cluster)

I'd try my fobs on another car, but i don't have any friends with vettes. But as said above, I don't think it's the fob. For whatever reason the RFA stops communicating with the other modules.... but it will work for a short period of time - that's the part the baffles me, cause I dunno if the RFA is really bad, or it's something else in the chain of commands.

Unplug RFA and plug back in, and it will work for a little while. Until it goes to idle mode, or whatever it does as time passes. Then it stops working. If I unplug/plug the RFA again, it will work again.

 

The codes you listed all point to the following diagnostic instructions.


Circuit Description
The serial data circuit is used to communicate information between each module connected to the serial data line. Each module is assigned a specific recognition code (source ID). This code is used to identify which module is communicating on the serial data line. Modules communicate with others by periodically sending messages on the serial data line. These messages contains specific information (or commands) a system requires to function properly. When a module receives a message it also learns the source ID of the system that sent it. This source ID is used to determine which module actually sent the message and for State of Health (SOH) monitoring. SOH monitoring determines if a module is unable to communicate properly. Modules periodically send a SOH message to each other containing their source ID. If a system fails to receive a SOH message from a module that it communicates with, then a DTC identifying what module did not respond will set. Any module that also cannot communicate properly, will also store the appropriate communication DTC that was assigned to that module.

Conditions for Setting the DTC
The RFA system sends out a State of Health (SOH) message to the Body Control Module (BCM), and no SOH message response was sent back.
Condition must be present for 5 seconds.
Action Taken When the DTC Sets
Stores a DTC U1064 in the RFA system.
No BCM output functions will be available to the RFA system.
No driver warning message will be displayed for this DTC.
Conditions for Clearing the DTC
This DTC requires an ignition cycle in order to change from current to history.
The RFA system receives a SOH message back from the BCM.
A history DTC will clear after 50 consecutive ignition cycles if the condition for the malfunction is no longer present.
Use the IPC clearing DTCs feature.
Use a scan tool.

Diagnostic Aids
If the problem is an intermittent loss of communications. Carefully inspect the serial data line and related components for the following intermittent conditions:

There is an intermittent open or short (to ground or voltage) in the serial data line.

Intermittent loss of communication with the BCM.

Damaged or loose star connector terminals.

If the serial data line is shorted to ground or shorted to voltage, all systems connected to the same serial data line will not be able to communicate properly. Systems capable of storing loss of communication DTCs (DTCs with the letter U as a prefix) will have these codes stored in their memory. If a DTC U1064 is stored in the RFA system, check for the same DTC stored in the Instrument Panel Cluster (IPC). The IPC also monitors the SOH message from the BCM. If the IPC has a DTC U1064 stored, check the BCM for an intermittent malfunction. If the BCM system does not have a DTC U1064 stored, check for an open in the serial data line between only the RFA system and the BCM. The RFA system must also be checked for intermittent operation due to a loss of power or ground to the receiver. After repairing a DTC U1064, clear all DTCs from all systems capable of storing this DTC.

If the DTC is a history DTC, the problem may be intermittent. Perform the tests shown while moving related wiring and connectors. This can often cause the malfunction to occur.

 

Can you display your tire pressures on the DIC ?????

If you can, your RFA is working. Your fobs need replacement.

 

Tire pressure displays, but explain the RFA codes?

If it were the fob, would the RFA be having communication codes with the IPC, BCM, and PCM?

So far i think japc5 is onto something, it has to be the communcation between all the modules, the databus or star bus, or whatever it's called... that seems like it's gonna be tons of fun to troubleshoot though

 

The Uxxxx codes are common on a C5 Corvette. The computers are connected by a "Class2 serial data bus" which is about the speed of a dial-up connection ..... in other words ... SLOW .... and there is a lot of data on the network .... the PCM is constantly sending out data about the engine and vehicle .... and all of the computers are supposed to send "State of Health" messages at regular intervals.

Delete the RFA Uxxxx messages and see how long it takes for them to come back ...... the RFA transmits tire pressure data at regular intervals to the IPC .... it receives data from the PCM (at engine start the RFA receives the barometric (outside air) pressure from the PCM), and the RFA communicates with the BCM when, for example, you are programming the TPMS and the RFA wants the horn honked to indicate it "learned" a sensor, or whenever you press the LOCK/UNLOCK buttons on your key fobs.

The RFA is much more "involved" with the TPMS ..... if that system is working, the RFA is working on the receive side.

When you "program" the fobs through the DIC procedure, when the system indicates FOB LEARNED on the DIC ... that shows that both the transmit and receive sides of the RFA are working.

I'm betting that your fobs are getting "old" .... if you search on "fob" and, say, "1999", you will be surprised how many people in the last few years have had to replace their fobs.

 

believe me, it is your fob(s), replace them. They get old and solder connections loosen. Someone fixed this with a microscope and re-soldering connections. It happens with old, used fobs.

 

I agree totally. For unknown reasons after 7-9 years, they start to fail and once they do, they never come back to normal. I asked GM to tell me who the manufacturer is so I could get the schematic of them but they refused saying to contact the dealer. The dealers don't have a clue. I know they are assembled in Mexico but no one will fess up about who makes them. There's been a few cases of bad batteries or bad solder joints, but usually they just die and all you can do is buy new ones.

 

This will sound strange but,,,make SURE that your 12VDC battery is in good condition and able to main at least 12VDC when the battery sits over night! That was my issue when my fobs would die.

When the battery is weak, it WILL caues a lot more NO COMMS issues than normal..
Can you RE Sync them back in operation once they drop off line???

Try the resync procedure and see waht that does for you.

BC

 

I checked the battery with a DMM, measured 12.6V w/ car off and sitting parking and not running for the last 12 hours. So that shouldn't be the problem.

Guess I'll just bite the bullet and by a new fob to see if that is it.

I'd really like to replace my RFA, FOBs and TPS's with a later model (2000+), since the batteries in my TPS's are dying, and the 97-99 TPS are so much more money.... but haven't read of anyone successfully doing that.

 

And what if the tire pressures don't display??? I'm having the exact same problem as of today, no tire pressure sensors and the key fob is dead. What's the solution????

 

How old are your TPS. They could be bad and the FOBs could be bad. The dealer and Autozone (at least in our area) have FOB Testers that tell you if your fob is transmiting.

BC

 

Thanks Bill. However, for both to fail on exactly the same day doesn't seem to be a coincidence. The odds of that would be beyond what I could calculate. Got to be something in common, say like the car's battery?????

Padrino

 

Just curious, If you use the fobs to lock the car (so the alarm is set) then the fob stops working, how would you stop the alarm from sounding?
You would use the key to enter the car, but this would trigger the alarm.

Thanks

 

No, manually unlocking the door from the outside with your key turns off the alarm.

In other words, if you lock the car, say using the fob, with the windows open, when you return to the car if you reach inside and unlock the door from the inside the alarm sounds. If you unlock the door using your key from the outside, the alarm will turn off and not sound.

From page 2-4 of your 1998 Owner's Manual ....

"If your theft-deterrent system is armed, unlock the doors only with the key or the transmitter to avoid setting off the alarm. See “Universal Theft-Deterrent” in the Index."

 

No, the fobs don't work to lock or unlock the car. I had the car in the garage so I don't lock it and when I backed out I noted the tire sensor warning. Took a look around and all tires were fine. Drove it up to speed and still no tire sensor info. Parked and went to lock the car with the fob and noted it didn't work, so manually locked the car and then unlocked it with the key.

Oh, by the way, I have 2 fobs and both stopped working the same day along with the tire pressure sensor. Likely, it's a central problem with the car, not the fobs or the tires.

Padrino

 

Happened to my 99........don't waste $$ on used ebay fobs, spring for a new one

Or take a search on ebay for

97-00 C5 Corvette Tire Pressure Sensors & Reciever KIT

Get all new style sensors, receiver and fobs for $350

 

Good to know, thanks