I posted this on 3-16-2020: Sorry guys for the lengthy post but I figure the history would help for some one to figure out the problem. Plus below this post is current situation with this on going issue.Help..... occurred 3-16-2020

I parked my 97 C5 overnight outside it has frost on the car. I drove to work this morning 25 miles. When i was roughly 5 miles from work my traction control light and abs light came on and the message on instrument cluster says:service traction system.I pulled the code 28-Tcs 1227. IThe car was running fine. At work I googled this code and brought me to this site some one posted who got this code. Member responded to this post says "left rear abs sensor/corrosion in connector or bad abs wiring or sensor but the poster never posted if this was the problem. So I'm thinking I'll check left rear abs sensor/wiring ddamage/,or check for corrosion this weekend.Since work was slow and dead i took off rest of the day. Now it was snowing mixed with rain so the roads were little bit wet so is the car.I left work started my way home. When i was like 5 miles away from home i was getting same message and codes but when I pulled into drive was and into garage I got message reduce engine power and the motor was running rough. So i shut off the engine and pulled the codes. This time I pulled following codes : BO-RFA C2120 H C, 28-TCS C1278 H, 28TCS C1227 H. 10 PCM P1221H C. SAYS ON CLUSTER MESSAGE",REDUCE ENGINE POWER. Now I had very same if not similiar problem with the car same if nit very similiar codes and messages last year. That time i washed my car with a pressure washer at work when i was like 3 miles into driving home my engine eent into loss of engine power had the exact same light and messages and i'm pretty sure same DTC codes as stated above. At that tine I deleted the trouble codes drove the car it was running fine till like couple of block the reduce engine power message came on and the engine went into reduced power mode plus I think exact exact same DTC codes were on. After keeping my car inside my garage for sbout 5 days I started the car up and it was idling fine, no DTC codes or reduce engibe power message came on. I drove the car around for few miles and longer and the car was runn8ng fine and normal like this problem never existed. So I thought to myself ok when I pressured washed the car and i did blow into both fenders filler covers electrical connectors or the pcm mounted on right side inside fender or abs sensors and wiring connector must of got wet and once dried out now it's fine since it dried out.

I'm writing and posting this from my phone be cause i do not have internet at home. Hopefully everything i need to write down is clearly written since it's difficult for me to proof read this cry for help post.



Help me guys let me know what is csusing this problem. There got to be a person out there who had similiar if not exact problem I'm having and foxed it and knows the fix. I don't know much about engines and cars, i love this car. 1st time owner. I'd hate to have this problem everytime it rains or my car is wet. Or have to get rid of the car. I've invested way to much into the car in interiors and uograding shocks and sway bars. I'd hate to sell this car if i can't find the problem.

3-16-2020 Ok, I cleared all the codes car was driving fine till about .3 miles into driving the engine reduced power and the message "reduced engine power " message came on and idling rough. I pulled tge codes the following codes pulled from DTC: 28-TCS C1278 . 10-PCM 2 CODES (P1120 H/C, P1221 H/C) AND "Reduced engine power" message.

NOW current update as of 3-25-2020 :

I kept my car inside the garage for 8 days when i got home from work I started up the car and it was running fine, no messages on message board as i stated above. I drove the car for 2.9 miles exactly and again no message came on the messages board and car driving and running fine like nothing ever happened. I pulled the codes and the following codes came on. Codes: 10-pcm P1571 H (asr desired torque- I have no idea what this means but since it's history code not current code I know i have nothing to worry about). 28-tcs C1278 H (TCS Temporairly inhibited by pcm. I know it's only history code so no need to worry on this), RTD- NO Communication(real time damping- Do i need to worry about this message ? what does tis message mean?).

So, my plan of attack is to check and clean all abs sensor connectors and wiring, engine bay connectors and grounds in engine bay in next month or two in good warm weather. Since the car is running fine now like nothing happened can anyone shed some light as to what the problem maybe to cause this problem? It appears to me thus far this happened when it is wet or raining outside where something gets wet or gets moisture on it.
Could the Tps sensor be bad?

Any input is appreciated.......

 

A failing ignition switch can generate all those codes and symptoms. A clue is that symptoms change or go away after shutting down and restarting. Symptoms come back at unpredictable times until the switch fails enough that the car won't run. I don't know of an easy way to absolutely diagnose. My car is on its third ignition switch.

Others have reported similar symptoms caused by loose or bad grounds, especially the ones from under/ near the battery, from the block to frame and the one on the back of the head(s).

More here from a search for- grounds

https://www.corvetteforum.com/forums...t-the-maf.html

 

OP I didn't read your entire post, however can run a search for each code on Google, you should find some ODBC pages that describe the errors, symptoms, workarounds and/or solutions. Good luck.

 

I am attaching a PDF file with the description of each code in your post. The file doesn't include the diagnostic procedures for the codes but I can add them if required. This info is copied directly from the 1997 Factory Service Manual. As others have said you could have an ignition key issue but your last update indicated just 2 codes and both are related to traction control. Your idea of checking grounds is what I would do first followed by going through the voltage side of the circuits and checking to make sure the voltages are correct once the grounds are verified. You are working on a 23 old car so there can be a lot of corroded, dirty or broken connections/wires. The fact the failures change and you seemed to get some ABS Codes (most C codes are ABS codes).

You have a rear mounted EBTCM which is probably more susceptible to environmental damage than the front mounted EBTCMs that came on the mid 98 and newer cars.

Bill

 

Thanks for your input Bill. I read your post on cleaning the grounds and connectors. Great write up. I'm learning alot from you and appreciate your help. Today I started on inspecting and cleaning up the grounds and connectors. I removed the ground 101 on driver side and removed the male connector. As you can see from the photo contacts look good no corossion just the lower contacts are oily and dirty and female connector looks good has accumulated lots of dirts and oily. I don't understand how the oil and dirts/debris got inside the connector. The 101 ground welded thread to the bottom on frame paint is peeling off and around the frame I sprayed down with WD40 and wiped it off. Do I need to strip/remove the paint and some rust that's there off the thread before i put the ground back on the 101 or is it ok from the photo you see?

Tomorrow I'm going to remove the oils and dirts from the male and inside female connector with contact cleaners then wrap the connectors with that elastic tape. Now do i put dielectric grease inside the connectors?
Here's the photo

Ground 101 male connector oily and dirt debris lower prongs.

Ground 104 below battery. Rusty

Ground 101 frame threaded stud to frame. At bottom threaded stud to frame paint peeling off and can see some rust on frame. Ok to leave like that or do i need to grind off paint and rust to bare metal before i mount the ground on that stud/frame?

Hround 101 famale connector inside oily and dirt/,debris inside
Ground 104 below batter as you can see its pretty rusty.