More codes after changing 12v battery a week ago

The reoccurrence of DTC P0607 is troubling. How likely is it that the replacement HV ECU has a problem? This is very strange.

The left and center brake lights get their power from the same source as the right brake light. 12V power goes through the 7.5A STOP fuse, then through the brake light switch. There is a junction connector which connects the three lights together. Maybe that connector is having a problem. Also check the ground connections for the lights. I don't think this problem is related to the HV ECU, but it may be indicative that the vehicle wiring harness is starting to get flaky, and if so that would be one reason that the car would eventually end up in the salvage yard.

Mobile, AL current weather shows 100% humidity. That may be part of the problem with the wiring. Has the car ever suffered flood damage?

 

I'm a bit perplexed; these two codes seem to go together:

C1249 Open in Stop Light Switch Circuit
P0607 Control Module Performance (in CC section)

I think Patrick is sort of on the right track. My interpretation of these two codes is that the control module is not able to function correctly as it is getting bad data from the brake switch. I'd be looking at the brake switch a bit more closely and be doing some diagnostic testing there. It wouldn't be the first time a brake switch went bad. Focus also on the junction connector which connects the three lights together mentioned by Patrick.

There again, I could be completely off track.

 

In post #33 the OP says he replaced the brake switch.

Since the car worked OK from January to April, I am wondering whether the issue might be climate-related, which would imply flaky/intermittent wiring. The OP lives in an area that is currently showing 100% humidity on weather reports.

The wiring diagram shows there is only one connection from the brake light switch to the HV ECU so if the two processors within disagree about whether the brake pedal has been depressed you would think the intermittent fault has to be internal to the ECU.

So I guess if I were the OP I would buy yet another ECU to see what happens. His experience has shown that the first used ECU was definitely faulty since he could not configure it to operate. Could it be that his original ECU and the second used ECU both have an intermittent connection within which is causing the two ECU processors to be out of sync?

 

You have a better memory than me, Sir. That is a few posts back.

But I guess it is possible that the brake switch has developed a fault since, though.

 

dim and flickering tail light sounds like a bad ground wire...check the wires going into the hatchback from the roof..i had a ford wagon with tail light issues no one could find, turns out the wires had pulled apart inside the black covering from the body to the hatch back..look for breaks and see if the wires have pulled out of the connectors ..

 

I actually don't think the brake switch is the problem if at least one brake light is working correctly.

Regarding another ECU, if you buy another used one you might try to get one from a 2008 or 2009 model year, from a part of the country that does not experience such high humidity.

Your car is 9 years old, I understand you've owned it for more than 2 years based on one of your prior posts. That post has a picture which shows the same DTC that your car continues to log as of yesterday, so there has been no improvement despite your efforts.

Are you able to return the used ECUs that you have already purchased? If not, you might be interested to open one up if the covers are not too hard to take off. Use a bright light and magnifying glass to inspect the solder connections around the two processors if you can find them. Look for two integrated circuits that have the same part number, which have a relatively large number of connections leading to them.

You would be looking for any cracks in the solder connections, or solder that looks dull or pitted.

I do not recall very many owners complaining about P0607 so this issue is pretty rare.

 

Have you looked at the inside of the brake discs? If brakes wear one side more than the other your caliber sliding pins need lubrication.

 

I do not think the stroke sensor is at fault.

The brake light switch consists of two separate switches. One switch is normally open and the other is normally closed. Then when you press the brake pedal to activate the switch assembly, the normally open switch will close while the normally closed switch will open.

The HV ECU expects to see 12VDC coming from one of those switches at all times. If it gets 0 voltage from both switches then it assumes the switch assembly has failed.

You can test the switch assembly by measuring resistance across the two switches, then pressing the brake pedal to confirm that they work (or else find they do not work).

I am not a proponent of buying aftermarket parts in general. However since you already bought the switch assembly, I suggest that you test it if you are concerned about its functionality.

I have a suggestion for something else that you can try: Buy a can of electrical contact cleaner spray at the Walmart auto chemicals aisle, or your local discount auto parts store. Remove the brake light switch wiring harness connector and spray the connector and the switch terminals. Have a paper towel available to catch the overspray and the cleaner dripping off. After the cleaner dries, install the wiring harness connector. Also remove the wiring harness connectors from the HV ECU and spray the connectors and the mating terminals on the ECU.

Do not use a cleaning product other than electrical contact cleaner. If for whatever reason you cannot obtain this product locally, use isopropyl alcohol which you can get at any drugstore. I use this in 91% strength, to clean electronics parts and printed circuit boards.

After testing the brake light switch and cleaning the terminals, if the HV ECU still logs the brake light switch fault code, another test is to measure voltage at the ECU wiring harness pins which relate to the two separate switches, using the electrical wiring diagram to identify those pins. When the car is READY, measure voltage at those two pins. One of the two pins should measure ~12VDC when the brake pedal is up, and the other should measure that voltage when the pedal is depressed. If the voltage measurements are correct but the ECU logs the fault then you will know the problem is with the ECU. If the voltage measurements are not correct then there may be a fault with the wiring harness. This assumes that the fault is solid - if it is intermittent then the fault may not appear while you are testing.

 

Yes, the one brake switch assembly contains two switches inside. There should be at least four wiring harness terminals.

The adjustment spec is 0.020 to 0.095 inches of clearance between the brake light switch and the area of the brake pedal which contacts the switch. I don't know what would happen if the switch is not correctly adjusted.

 

all the best.