3 Brake warning lights come on - no codes stored?

Or stick a jumper wire between TC and CG ....

 

Nope. Never see the problen on the wifes '04. My friend from work never reports the problem on his '07 so must be particular to this year model. I am pretty sure the antilock module assembly is year specific as replacing these you must match your part number according to most authorities like Harrison interchange and ebays used parts built in effectivity interchange and their salvage sellers notes. I do upon ocassion temporarily when using techstream to watch some weak module or weed out location of block of module pair that is intermittiently mostly when warmer out kicking out a APO80 or whatever exact code causes the dreaded red triangle if death that translates to Hybrid pack replacement that is really just a 1 25Vdc difference between any blocks) see a data lack of communication between computers that never sets a pending or hard code. This might be the root cause but simple educated guessing here have zero proof.

 

Have done those reset methods. Both as in paperclip one and Techstream but problem of 3 yellow lights just reoccurs at random and is not a relevant fix as it goes away on its own quick enough to not require resetting.

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Seems a little bit overwrought (and when I look for those quotes, they seem to have come all from one thread, where one poster said a bunch of scary stuff).

One can find pictures of the vaunted special service tool ... it's a wire (with crimped-on pokey ends).



It certainly is good advice to "count twice, insert once" to make absolutely sure you know which pins 4 and 13 are. If you anticipate checking codes often, it can be easier if you build a thing like I did:



The TS and TC switches are both center off, up for ON, down for momentary ON, because the manual has various procedures where you make things happen by not just tying the signal to ground but by pulsing it some number of times, which is clumsy to do with a wire. AB (only for Gen 1, later Prius gens don't have an AB circuit) is only a pushbutton, because the only procedures that use it in Gen 1 involve pulsing it some number of times.

But the basic "blink me out the diagnostic codes" command is just to connect TC to ground, period. Nothing fancy. And it does what it says on the tin.

I did just recently learn that TS is a different pin number for Gen 2 and later than for Gen 1, which is why my little box now has the newly added slide switch at the bottom to select which pin the TS switch goes to.

This rides around in my glove box all the time, unlike a laptop with Techstream, which can pull a lot more information, but is just too bulky to have live in the car.

-Chap

 

Nope nope nope nope nope ... 4 and 13.

CG has always and forever been pin 4 (it's defined in the OBD-II standard). TC hasn't budged from pin 13.

It's the TS signal that changed pins between Gen 1 and Gen 2. That doesn't concern you, unless you later need one of the procedures that involves using TS.

For blinking out codes, TC (13) and CG (4) are all you need.



Be sure you pay attention to which way the DLC3 connector is mounted ... it may or may not be wide-side-down like that picture.

Codes will continue blinking as long as you have the pins jumpered. You know you've seen the whole list when it comes back around to one you already wrote down.

-Chap

 

Sounds like a computer control module going bad or sensors.

Posted via the PriusChat mobile app.

 

A couple reports upthread were of lights with no codes to read. If there are really no codes, generally sensors would be ruled out (a sensor problem would be reported with the codes telling you what sensor problem you have).

ECU going bad would be a possible explanation for weird lights with no readable codes. The only thing is, by experience, a "lights but no codes" post on PriusChat usually means "lights and the code reader I was using did not retrieve codes", and ECUs, being solid state electronics, really don't all that often go bad.

That's why, before jumping to any conclusion like "module going bad", I'd suggest the simple, no-scantool-required built-in blink-out-the-codes test.

-Chap

 

I have the same issue on my 95. Was this issue ever resolved? Thanks

 

Slipped a decade?

Welcome!

 

Well, let's get started, first by figuring out if it's likely the same issue or not. As you tagged on to a "lights but no codes" thread, I assume you've already tried to pull codes with an inadequate reader and it didn't show you any. Have you pulled them yet with either Techstream or the TC-to-CG jumper wire, and what were they?

-Chap

 

Though I've used this box without issues for years to do the non-Techstream "jumper TS or TC to CG" kinds of procedures, the last couple times I've gone to use it, it the car's Master Warning Light has come on immediately, along with flashing PRNDB segments and a message about the parking mechanism. Unplugged again, cycling the power button leaves the MWL on and the "CHECK HYBRID SYSTEM" message. Yuck. Fired up Techstream, saw a bunch of comm errors logged, and cleared them. Warnings go away.

Plugged my box on again, and woop! back with the MWL. Simply from having the box plugged in, not using the TC or TS switch or the AB button. I've had the box apart, looked for shorts in my wiring, ohmed things out, didn't find a problem.

At least I figured out the comm error warnings will go away by themselves after a few drive cycles, so I don't have to keep lugging out the laptop and Techstream to clear them.

The ScanGauge that I have plugged in all the time never has that effect. And this box used to do just what I built it to do; it never caused comm errors just by being plugged in before.

Only difference I see at the moment is that the ScanGauge cable connector has gold-plated pins. I built this box on a cheapie J1962 connector with unplated pins. And I've had it about ten years now, riding around in the glove box. I wonder if the pins are just that bad now.

I have another cable sitting around with gold-plated pins, and I can plug that one into the car and it doesn't trigger comm errors. Guess maybe I'll rebuild the TC/TS/AB box using that ....

-Chap

 

Success ... the resurrected Ts/Tc twiddler built on a J1962 plug with gold-plated contacts is rock-solid, I can plug it in or out with the car off, on, or ready, no glitches, no comm errors, the twiddle switches do just what they're supposed to, nothing weird happens.



My old one with the unplated contacts worked equally well when I first built it, but had gotten to the point where it would cause comm error reports from several different ECUs, just by being plugged in at all.

-Chap