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I'm hoping the collective wisdom can help me solve this problem. I'm based in the UK, and this is a USA spec car. It's a 1997 coupe. I've scoured this forum and can't find the answer hence a new thread
I bought the car recently, and it came with the TPMS issue (not working, XX for the pressures). It also came with no electronic fobs - just 2 physical keys that open and lock the car. I need to get this fixed, as otherwise due to UK law, I'm unable to drive the car next year.
The DIC brings up the following codes:
B0-RFA NO COMM
SCM- NO COMM
60-IPC U1176 H C
RTD NO COMM
Points to note:
I've located the RFA in the rear trunk area. It looks in great condition, the circuit board looks like its had no damage.
I've tested both the power and ground to the RFA (by testing current across those two wires). It shows 13V so I know those two are working.
The BCM looks in good condition, no sign of water ingress etc. There is some taping so some work may have been done in the vicinity.
The IPC code and RTD code are more recent. The codes don't change whether the RFA is plugged in or not.
Fuse 27 is fine.
As I'm based in the UK, it's far harder and slower to get cheap parts here so can't just 'replace everything'!
If I try and code a fob or the tyres, I don't get to the point where I can actually code, it stops at the stage before that.
My questions:
On another thread, someone mentioned unplugging the SCM module and seeing if that made a difference. Why would that change the RFA error? I have no memory seats or anything (although they are powered)
On another thread, someone mentioned testing the continuity between the pink RFA wire and the BCM, but I couldn't see any more info on which connection that is, can anyone advise?
What diagnostics are there to figure out if it's a BCM / RFA / something else error?
What order would you suggest 'replacing' things if points 1 and 2 and 3 don't help, to try and solve the issue? I've seen salvage '97-'00 RFA modules for about $150 (guess that would tell me if that was faulty), replacement key fobs for '97-'00 for about the same, BCMs for about $300.
When a Module that is connect to the Serial Data Buss, has an issue, it can cause other modules connected to that Serial Buss to have communications issues and fail to function. The SCM is one of the modules that Reak havoc on the Serial Data Buss. The other modules that can cause serious comms issues are the LDCM & RDCM. If you see any U Series DTCs, that is a communications issue. The BCM is basically a small router that ALL the modules on the serial data buss communicates with. The BCM sends out a state of Health data message to all the modules and looks for the return communication. If it doesn't get the message back it sends out a DTC for that module.
If it were me, I would disconnect the SCM connector and see if you get functionality from the other modules that are having comms issues. The SCM is in a bad area and often times the Module connector gets damage or WET. Carefully examine the connector, wires, Female pins inside the harness connector etc. See if you see any chaffed bare, cut wires or corrosion in the connector. . See if there is moisture under the seat or behind the seat by lifting the carpet and feeling the Jute underlayment.
Like you stated, If you have POWER & GROUND to the RFA Module, It should function. The RFA controls Key Fob & Tire Pressure Monitoring functions. Do either one of those function at all?
Read all of the DTCs and CLEAR ALL of them and see what comes back.
BC
Last edited by Bill Curlee; 12-12-2023 at 11:25 AM.
The RFA Module is normally located on the drivers side of the car. Its behind the plastic trim over the wheel well area. Can you take a picture of yours? The RTD Module is located in the rear hatch area inside the LEFT Side storage Compartment under the carpet. on the front side of the well.
If you have the F-45 RTD Option, "IMHO" That would be the very first Modification that I would do to my C5 GET RID OF IT! Replace it with C6 ZO6 Shocks or some New Billstein Shocks. That is the WORST thing GM ever put on a C5 (other than the Cadillac Looking Exhaust Tips) LOL!
How many miles on your car? Is it Auto A4 Trans or Manual MN6 Trans?
Can you take your FOBs to a local Auto Parts Store and see if they have a TEST Machine to verify that your FOBs are actually working (transmitting a signal) ???
I recently stripped both my seats due to a motor burned out, the track 'slide' and them not moving. All fixed now, but I'll disconnect all wires going into the SCM tomorrow morning, and I'll post any changes to the DIC too. When I looked at the SCMs then they looked OK, but I'll inspect in more detail.
The TPMS do not work at all - if I try and register them, I go through the DIC options but fall short of the stage where I can program them as the next 'screen' doesnt appear.
I have never had any fobs, just the 2 physical keys, so I have no way to test any fobs (short of buying some - hence my 4th question.
I've attached the 2 photos of the RFA below
I don't think I have the F-45 RTD option (I have no stickers on the car that shows the option list). It's a fairly basic spec '97 with only one traction button in the middle. I've had a look for any boxes where you describe but cant see any. I'll look more in the morning when it's light.
I would believe that (if you have the OEM 97 TPMS Sensors), those batteries are DEAD.
If it were me, , I would just remove them and replace the batteries. Its a relative tedious job but its doable and saves a bit of cash. There are several YouTube vids that cover the procedure. If you decide to get new ones, REMEMBER, 97 -2000 C5 are one frequency and 2001 - 2004 are a completely different frequency. You MUST get the 97-2000 sensors!!!!!!!!!!!
There are two connectors besides the bcm which have a metal jumpering comb, this combs connect the seriel data buss wires together, you would need to find out which wire is the RFA module and connect a scope to see the pulses. You could of course remove the RFA module and send it to business that test and repair such modules here in the states.
PIN "A" (orange wire) is the POWER IN and the Black is the GROUND. The other one is the signal wire. You can power up the RFA and you should see a signal on the output wire if the module is functioning. You will need to use an oscilloscope to view the wave forms/output signal.
Like "mmartinez" stated, The TWO STAR Connectors in the passengers foot well can be accessed to see if the signal is getting to that point. Ther are TWO thin connectors to the left of the BCM. If you remove the TOP off of the STAR connector it isolates ALL of the wires in that connector from the others. The STAR connector with FOUR WIRES contains the Serial data wires for the LDCM, RDCM and the Seat Control Module.
Andrew - so just to clarify, you're needing to get TPMS functional due to UK law? Or are you just needing to shut down any MILs (idiot lights) in the dash?
Reading over your posts, the reason you're not able to get to TMPS or FOB relearn / training is because that is triggered by the IPC (or maybe it's the BCM) communicating with the RFA over the ALDL (pink wire) and apparently that's not happening.
Per Bill's diagram above I'd attempt to locate circuit 1045 in the passenger footwell, and test for continuity between that point and pin D of the RFA connector. I'm not sure where that instrument panel electrical center connection is located but that's another possible suspect.
I tend not to disagree with Bill much, but will say from experience you'll want to get new tire sensors (if you need them). I can find you some compatible ones on Amazon if that's an option, or I have some I can sell you assuming it's not a problem getting them through customs. But I would hold off on that until you can figure out if the RFA is connected to the ALDL.
One other thought I doubt is your problem but wanted to mention as another point of consideration - all the C5s not built for export were equipped with 315mhz tire sensors. In 01 they switched from ASK modulation to FSK modulation though still on 315mhz. So the early C5s needed one sensor and the late C5s needed another. I'm not at all familiar with UK radio laws, but 315mhz might be a regulated frequency in your country. Do you know for a fact the wheels have sensors in them? Perhaps they were mercilessly removed by customs officials?
In answer to your questions spfautsch, in the UK we have an MOT test every year, and your car needs to pass the test to be allowed on the road. This test looks at suspension, tyres, rust and loads of other things, but one such test is that if a TPMS system is installed, it should be working. In my situation, it clearly isnt I've seen somewhere that you can 'delete' it for a track day or such like which may work, but I'd rather not risk it.
I've just removed one of the star connectors, and tested continuity to the pink connector on the RFA. There is no continuity to most of them, but one of them (the end one on one of the connectors) shows zero resistance, so looks like there's connectivity.
I've ordered a new RFA which I'll get posted to the UK shortly, and some USA spec TPMS sensors 315 mHz specific to my year. They were just the cheap ones off ebay, but that will be a good start. I've also ordered a replacement fob (the expensive one for the '97-00 years annoyingly!)
So that tells me that the wiring is fine (at least in that part). Is there a test to check that the BCM is working? If I'm doing an order of parts from USA to UK I may as well order a salvage BCM at the same time if that does turn out to be faulty! Or would you suggest just getting the replacement RFA delivered and see if that helps? Would a faulty BCM still generate a signal from the RFA that could be tested with an Oscilloscope? If so, that may be my next purchase - as would no signal suggest faulty BCM?
You didn't mention any codes for module 40 (BCM) so I think it's safe to assume it's ok. Further, if you get messages on the DIC when the doors or rear hatch are open that would be proof enough for me that it's healthy.
Good luck with the RFA module. I've no idea if any programming is required for it, maybe someone else can chime in on that.
Fingers crossed on the eBay pressure sensors. I'm something of a self-proclaimed TPMS guru, and have seen numerous horror stories here about non-compatible / non-functional sensors from eBay sellers.
In most states over here we have far more relaxed laws. In my particular state it's not required to be functional even on something with federally mandated TPMS (2008 and newer passenger vehicles). Even our emissions "testing" is comprised solely of verifying that the PCM shows a "green light" when checked with an OBD2 scanner. Though I've heard reports of certain chain shops such as Dobbs, Firestone and Pep Boys failing a vehicle if there are any MILs whatsoever such as TPMS, ABS, etc.
I don't think I have the F-45 RTD option (I have no stickers on the car that shows the option list). It's a fairly basic spec '97 with only one traction button in the middle. I've had a look for any boxes where you describe but cant see any. I'll look more in the morning when it's light.
It's on 97K, and an auto
Hello Andrew, the model year 1997 Corvette thru early model year 1998 Corvette's can be a bit of a challenge to repair as these cars systems can be unique compared to the later production C5's...
To provide you tech recommendations that is specific to your 1997 model year car, it would be helpful if you could post to this thread, your Corvette RPO Code Label (Service Parts Identification Label).
1997, Early 1998> White sticker located on the underside of the rear left storage compartment cover (on the driver's side) of the car, but look also at the other storage covers and post photos of the stickers or labels on these storage compartment covers.
Verify the Vehicle Identification Number (VIN) on the Service Parts Identification Label matches your cars actual VIN on the dash as this storage compartment cover may not be original to your car. as a side note, also take a look on the inside of the glove compartment door as there may be a very small chance the Service Parts Identification Label maybe be there...
The RFA Module is a PLUG AND PLAY module. A small portable scope is a very useful tool in diagnosing serial data issues and seeing the specific signals. If it were ME, I would NOT throw away your old RFA Module. Like spfautsch stated, I have seen people have issues with the E-bay TPMS sensors as most of them program differently than the OEM sensors. Sometimes they fail to be recognized period.
NOTE, A used BCM is NOT going to be of any use unless you can reprogram it security data. When it leaves the factory, its programmed to your car with the VATS Security data. The Key VATS chip must match the VATS resistance value programmed into your BCM. If you dont have a three position RTD Selector **** on the center console next to the Traction Control push button on the center console, you dont have the RTD F-45 Option.
Goose - sadly I don't have that sticker -I can see where it was but nothings there now. Nothing in the glove box either (even though that's later cars) I can't see the sticker anywhere! I've just got my build sheet from monroneylabels for $10 which is below - does that help?
Based on appearance I would venture a guess those will not be magnetically triggered. So you might want to locate an RF TPMS trigger tool - OEC-T5 is a generic model #. They're typically about $10 on amazon.
Hello Andrew, after reviewing your attached RPO codes PDF, your BCM should not be posting RTD NO COMM on the DIC...
I suspect the Body Control Module (BCM) is not original to your vehicle or properly programmed/flashed to your VIN RPO codes....
I dont mean to hijack this thread, but
Bill I have the same trouble with my 98 coup. you asked The RFA controls Key Fob & Tire Pressure Monitoring functions. Do either one of those function at all?
In my car the tire pressure system functions but the fobs do not. I have a good key fob from my 2000 and I cant even program that to match the car. I do have the RTD F 45 system
Find a big box Autoparts store and take your FOBs there and ask if they have a FOB TRANSMITTER TEST BOX. If they do, test your FOBs to see if they are transmitting a signal. . If both FOBs transmit, they should be able to be trained and work. Make SURE, that they are the FOBs for your model year C5. 97-2000 use the same frequency fobs 2001-2004 use a different frequency FOB and TPS
How are you attempting to train your FOBs to the Car?
Are you entering FOB training mode?
If you depress and HOLD the LOCK & UNLOCK buttons on the FOB for one minute, (FOB SYNC MODE) does the horn beep once?
I had the RTD (F-45) system on my first C5 (98 MN6 Coupe) I didnt build my C5. Someone ordered it from the factory and never completed the purchase. My wife and I both never liked that option. In my honest opinion, I would delete it and up-grade my suspension to a Z-51. ZO6 or better Aftermarket Suspension. , If you have many miles on the car, the shocks most likely have lost their nitrogen charge. The F-45 option is built on the FE-1 base suspension. Its NOT a performance oriented suspension.
12-12-2023, 07:44 AM
C5 RFA fault diagnosis
I've seen somewhere that you can 'delete' it for a track day or such like which may work, but I'd rather not risk it.
