C1247 ECU Skid Control replacement?

Either the brake pedal stroke sensor or the skid control ECU is at fault. I am wondering why your dealer did not suggest replacing the stroke sensor first, since that is less costly than the ECU.

I would suggest that you first replace the stroke sensor with a new part; then if that doesn't help, replace the ECU with a used part.

 

Yes, or else have a used part installed if your dealer is willing to do that.

Try autobeyours.com as a good source of used Prius parts.

Typically a Prius will be totaled as the result of a front-end collision since the SRS system would have deployed and there are many costly parts in the front that would be damaged. So it doesn't surprise me that the eBay parts are coming from cars with front-end damage.

 

Apply a jumper to pins 4 and 13 of the OBD-II connector; do a search for how to reset skid control ECU DTC.

 

My wife's Prius is a 2008 model 1224A (package 2 including VSC) with 71,000 miles.
Recently while my son was driving it, it displayed the common 4 warning lights on the dash:
BRAKES / ! / ABS / VSC
and the brakes became very touchy: grabbing rhythmically. The brake pedal itself doesn't pulse, but it's as if the brakes themselves are pulsing about once or twice a second. He drove it for a couple of days like this until he could get it back to me, then I drove on a couple of short errands-no change. I had a mechanic friend check the codes: C1247. He ran the Toyota Tech software and it came up with nothing out of spec. He did notice that there was a Tech Service Bulletin in 2012: T-SB-0174-12 "overly sensitive monitoring logic". Could this be the root of the problem?

For now he cleared the computer code: the warning lights are gone and the braking is normal again. I'm driving it carefully to see if I can tell what triggers the malfunction. So far 3 short trips and all seems normal again.

(Hopefully not to confuse the issue, but we had similar braking problems like this almost 3 years ago, at 50,000 miles. The braking symptoms were the same and the same 4 warning lights, but the codes were different: C2300, C1241, and C2318. The dealer replaced the 12V auxiliary battery, cleared the codes, and it was fine for almost 3 years. Even though we're getting a different code now, could it be time to replace the 12V battery again?)


I see by searching the forum that several people have had trouble with the braking system, often throwing code C1247. It also looks like there have been 4 different approaches to fixing the problem, but none of them seem to be definitive, often doing any combination of the 4 fixes and then having the problem come back.
1. adjust or recalibrate the brake pedal stroke sensor
2. replace the stroke sensor
3. replace the ABS ECU
4. clear the code

Has anyone determined what is actually causing the problem and what the proper fix is?

Thanks,
Gib

 

The following thread contains my comments on my 2007 experiencing this problem (at the time, the car was owned by my dad.) Basically, the dealer first tried clearing codes; then replaced the skid control ECU, then finally replaced the stroke sensor. The problem did not recur after that third service was done, the car has been driven 50K+ miles since the final repair and is now being driven by my daughter.
See my posts 45, 48 and 54 here:
BRAKE FAILURES ON 04+ PRIUS | Page 3 | PriusChat

 

Hi Gib,

Yes. I doubt that both the stroke sensor and the ECU had failed. Since the problem continued after the ECU was replaced, it is reasonable to me that the stroke sensor was the actual failed part.

As a general rule, if there are two parts that might cause the failure it seems reasonable to replace the less expensive one first, if you are the one paying for the repairs.

In my dad's case, Toyota was paying for it so we allowed the dealer to let the mystery unfold over time.

 

Gentlemen, I am having the same problem as described above. Where do you suggest I purchase a stroke sensor?

 

From one of the Toyota dealers that sell parts at a discount over the web.
parts.com is a source that I have recently started using. Basically that website will send the order to a Toyota dealer for fulfillment.