VSC, ABS, (!) and emergency brake light on

Tell us the history of this car: odometer reading, and was the car in a recent accident? Was everything working well prior to the engine misfire episode?

Regarding the various warning lights that are on, this is showing you that the skid control ECU is having a fit. Sometimes this will happen when the DC/DC converter within the inverter is not working, which lowers voltage on the 12V bus.

Did the lights come on when the powertrain was cold, or only after the car had been driven for a while?

Use a digital multimeter to measure voltage across the 12V battery when the car is READY. You should see 13.8VDC. If much lower, this shows you the DC/DC converter is not producing adequate voltage.

Then, if the voltage is abnormally low, make the car IG-ON (start from IG-OFF, then press the POWER button twice without depressing the brake pedal, so that all the instrument panel warning lights are on.) Open the hood and look for the inverter coolant pump which is behind the driver's side headlamp assembly. Listen to see if you can hear the pump, which sounds like an aquarium pump.

If you cannot hear the pump run, then it needs to be replaced. The inverter is probably overheating which caused the DC/DC converter to stop working. If you replace the pump the inverter may resume operation, or it may be fried and have to be replaced.

If you can hear the pump run, do you hear any air bubbles? If yes, this has to be purged out. Then look at the inverter coolant reservoir and see if you can observe turbulence in the fluid. If yes, this shows that you have good circulation.

 

Hi Jimmy Bob,

Our 2004 Prius (basic model with 52,000 miles up) just started doing exactly as you describe yesterday. As it happened it was booked into a Toyota main dealer this morning for a service but the guy came back and said they really don't know what the problem is but they think its in the 12V wiring???

They are trying to say it's nothing to do with the Hybrid system so is not covered under the 7 year warranty as it is outside the standard 3 year warranty on the rest of the car. Did you get to the root of your problem?

Patrick, our car is accident free and has been trouble free for the 3 years we've owned save for some starting issues which I've put down to us not keeping the start button pushed for long enough.
Yesterday and this morning was different though. When we started the car we got no lights on the dash. I could hear a sort of gurgling noise and then the engine started but still no lights. Turning it off and on sometimes the main battery showed empty then it would appear green. I put it into reverse and it went to go, still no lights, but also no power steering. I left it sit for a while and after approx ten minutes it powered up but had all the warning lights on - the parking brake sign, traction control VSC, ABS, red triangle and the red sign on the display came up but the car drove fine.
Drove it like that to the dealers, left it running until they came to take it inside. The guy told me after that when they turned it off to do the standard service that they had a lot of trouble to turn it back on again but they couldn't figure out what it was.
I'll get the fault code list on Monday but he was just describing the fault codes associated with each of the above ECU's saying they thought they were not getting the correct voltage.

I'll post more on Monday when I get the actual code list

Thanks in advance

Cormac

 

Hi Cormac,

A strange mix of symptoms. Is the 12V battery original or has it been replaced? If replaced, how old is it?

If the DTC mostly relate to low voltage on the 12V bus, then I'd examine the condition of the 12V battery and also see whether the DC/DC converter is providing the correct 13.8VDC output when the Prius is READY.

Looking forward to seeing the DTC list after you receive it. Thanks.

 

I replaced the 12V battery with a genuine Toyota replacement battery about 6 months ago when we were having trouble getting it to go to ready on start up (I subsequently suspect that we simply were tapping the start button instead of keeping it pressed until it started). I asked the guy to check in case the 12V battery had failed but he said it was fine.

The DC/DC converter lead sounds prominsing, I'll keep you posted once I get the DTC codes.

 

You can check the 12V battery and the converter (charging) voltage without tools using the procedure given here:
http://priuschat.com/forums/newbie-forum/73400-weird-stuff-happening-mpgs-dropping-test-battery.html

Techs sometimes rely on a pass/fail tester intended for batteries in conventional cars, which may call as little as 10V a "pass". But that's not enough for reliable Prius operation.

 

Hi guys,

Well, they found the problem, they said it had a faulty IGI Relay Module. Replaced and all seems well with starting anyway. However I do think it feels sluggish but I could be over sensitive. Also fuel economy seems real bad (29mpg after 14miles) but I haven't reset it yet after the service, when I started it at the dealer it was showing 13mpg after 5 miles but I assumed this was down to running in the garage.

The fault codes thrown up were:
Hybrid Control
P3108 Lost communication with A/C system control
U0129 Lost communication with Brake system control module
U0146 Lost communication with Gateway "A"
Cruise Control (which I don't have!)
U0129
ABS/VSC/TRC
C1242 Open circuit in IGI/IG2 Power Source Circuit

Now they charged me €550 labour (over $650 USD) for the pleasure of finding the fault. My Prius is out of normal warranty but still in Hybrid warranty. The question is, what is the IGI relay module and is it part of the Hybrid system or truly seperate as they claimed as obviously I want to try and claim this back from Toyota Ireland if possible.

Thanks in advance for any help you can give.

Cormac

 

Hi Cormac,

Thanks for providing the resolution to your problem.

The IG1 relay is located in the driver's side junction box under the instrument panel (at least in LHD vehicles). It provides 12VDC power to a variety of circuits. It is not covered by the hybrid system warranty.

Your mpg doesn't seem bad to me:

13 mpg after 5 miles means you used 0.38 gallons to cover that distance, and as you said it seems likely that was due to the shop running the gasoline engine while the car was being tested.

29 mpg after 14 miles means you used 0.48 gallons total. Hence you used 0.1 gallon to cover 9 miles, or 90 miles per gallon?

 

Hi Patrick,

Thanks for the reply, wrong answer for my wallet though

I was just too p!ssed off having paid for the repair to do the maths on the mpg myself. Still its nice to have it back again.

Worst part is that I have to put it up for sale and so won't get a chance to let it repay itself with another 3 years of rewarding motoring. We've got 2 kids under 4 and with another due soon there's just no way of working 3 child seats in the back I was hoping that the Gen III model would be wider and able to take 3 smallies as I would stretch to one but it seems no bigger that way.
We're looking at changing to a Honda FRV which as a 6 seater offers great flexibility but as soon as Toyota bring out a suitable hybrid in this market (I know they have a Previa hybrid in Japan market) we'll be back to electric motoring.

Cormac

 

Is that a real screen name !!!!
This is a good posting series. I have these problems plus others. Can someone please take a picture of the pulled electronic part. Please Please.
VSC/ABS have always been sticky issues to resolve on alot of vehicles.

 

Yesterday I had all 4 wheels on my 2008 Prius (30,000 miles) aligned at a Goodyear Tire Dealer. They used an EZ-shim on one rear wheel. Now the emergency brake, brake system warning, ABS, and VSC lights are on. My scan gauge says "no codes." I disconnected and reconnected the 12v battery - no change. The car drives normally. What would cause this, and can I fix it myself? Or do I need to take it to a dealer?

HMG

 

Were the warning lights on immediately after the car was serviced, or did they turn on some time later? If this happened immediately, then the problem can be attributed to the alignment process, probably some mechanical shock was transmitted to a brake component which caused the skid control ECU to log the fault.

I've previously posted regarding how to clear DTC logged by the skid control ECU. Basically this involves putting a jumper between two pins of the OBD-II socket. As you discovered, disconnecting the 12V battery does nothing when it comes to skid control and SRS ECU DTC.

If the warning lights took some time to come on, then it will be necessary to dig deeper. Have you checked the inverter coolant pump to see if it is running?

Don't count on the Scan Gauge to show DTC produced by any ECU besides the engine ECU.

 

Apparently the lights came on when he started the car after completing the alignment. They were on when I picked up the car. The inverter coolant pump is working, so I'll try the jumper trick.

 

HMG: In case you did not find one of my earlier posts on this, see my post #9 here:
http://priuschat.com/forums/gen-ii-...5-miles-warning-lights-today.html#post1184545

 

The ritual with the jumper worked. No lights now. Thank you!!!

 

Hello guys , sorry for posting on such an old thread but I am need of help, I too am a victim of firestone, my 2006 Prius was none the better except for it chewed up my old tires and since I just bought new tires I wanted to get it done correctly for once. No lights were on the dash except for the "Brake" light which was there when I bought the prius, it was a broken E Brake switch which has now been replaced.

The lights appeared immediately after my lifetime alignment was done so from the sounds of things I am beginning to think that the young 20 year old tech damaged my speed sensor.
The great thing about this is that Firestone is taking full responibilty for the lights, they know and admit they were the ones that caused the problem and apologetically asked me to take it to the dealer to have the codes reset because "our OBD Tool cant reset those codes, only toyota can" and asked me to bring them the receipt and they would reimburse me for all costs

My Stealer wants $120-$160 just to hook it up , what do you guys suggest

 

I'm not sure what the problem is, since Firestone will cover the dealer service charge.

 

I understand however I am afraid Firestone will renig and I will be stuck with the bill since I don't have anything in writing.
Will the diagnostic confirm that the problem is in fact the sensor?

 

I can't promise what the dealer tech's diagnosis will be.

 

Ok so I just left the dealership and they said that it is not my speed sensors, they all appear to be fine and undisturbed. They explained to me that the skid control module was not functioning at all, that it wasnt learning the new settings, everytime they attempted to save the new settings it would send out the fault code and not save, the code it was giving was

DTC C1345/66 BOT LEARNING LINEAN VALVE OFFSET and
DTC C1368/66
DTC C1365 LINEAR VALVE OFFSET
They told me upon inspection found SKID CONTROL MODULE ECU/ACTUATOR ASSEMBLY INOPERABLE - REPLACEMENT REQUIRED - COST TO R&R $2390.00 (includes bleed brake system and calibrate ASLL Sensor

I doubt Firestone will flip the bill to replace this unit, the dealer said it was pure coincidence that this went out at the same time as the alignment, which I honestly find hard to believe the car was running great with absolutely no issues prior to it going to Firestone

Any pros here care to help out, I cannot afford a $2400 repair, the ECU alone i $1600 new, I found quite a few used ECU's on Ebay, is this something I could R&R myself?

Thanks for any help