Prius no start -- two dealers can't fix

[whmracer99]

I have not been able to find an issue quite like mine -- I'm hoping someone can provide some direction on next steps for my '02 Prius.

I am a rebuilder in Atlanta and have an '02 Prius that we purchased with light front end damage. We repaired/replace the damaged cosmetic pieces with Toyota factory parts from a salvage vehicle.

The car only starts when the 12 volt battery has been disconnected for a period of time. The car runs and seems to operate fine for 5 to 10 minutes and then the "red triangle of death" shows up and the main battery warning light is lit. After that the car fails to start (only a slight click is heard when the key is turned to the "start" position).

Two Toyota dealers have had the car and both have wiffed at fixing it. The short list of what they recommended and has been done on the car is replace the main power cables to the traction battery, charged the traction battery (twice), replaced the main power relays, and replaced the invertor (replaced with a used part). We also replaced the throttle body as the throttle motor housing was cracked, and the oil control valve for the camshaft due to cut wires.

Net-net is that the car still functions the same as it did when the dealers got it.

Toyota now says that they will refuse to do any further diagnostics on the car until both the invertor and transaxle are replaced with new parts. Their stance is that both those need to be replaced at the same time or the part left in the vehicle will damage the new part. The funny thing is that they can't guaranty that will fix the problem nor have I seen anything in any of the on-line posts that confirm the invertor and transaxle have to be replaced as a unit.

I do see some corrosion on the traction battery cell connections but the dealer swears they have checked it and there's no issue with the main battery (even after both dealers told me initially it wasn't holding charge).

I like these cars and have had several that worked great but this one is driving me a little crazy so I'm hoping for some help here from the experts (as opposed to the dealer who I would characterize as less than "expert").

I can supply existing codes, etc., if you need more info but I would really appreciate some guidance on next steps OR if there is someone in my area that is good with these cars I would consider having it looked at by a real expert.

Thanks for your help.

[fred s]

I think the codes are important in diagnosing what the problem is.

[naterprius]

Is it a problem with the Transponder key? This car uses the older style security RFID key. It must be programmed for the car.

Nate

[hobbit]

The codes, particularly those stored at the time of the xmas-tree
failure, are the most important thing. Simply parts-swapping is
the blind bumbling way to go at it as you've said, and most dealer
shops aren't actually interested in a point diagnosis. With minor
front-end damage you might be looking at bum wiring harness or
connector parts, but in some critical control location. How about
the low-voltage wires that run down the front of the engine and
split out to the transaxle? Are they in good shape? Did you pull
all the connectors and look at 'em [which can have the effect of
reseating a questionable connection sometimes too]? Are the HV
wires actually dinged at all, or anything coming off the inverter?
Does the engine idle stably in neutral once the car starts? Is it
normally driveable in the time before the codes light up? Do you
have a scantool of any sort such that you can pull your own codes
even if you can't necessarily see their meaning right away [i.e.
can look them up online]?
.
_H*

[tochatihu]

I don't think this will be an easy one. Absent a complete list of DTCs, we must assume that the HV busbar corossion *is* a factor, and that the parts you replaced (throttle assy, oil control valve etc.) may not be functioning. With much time and patience you could confirm the function of the latter group by swapping into an otherwise-good vehicle.

Do you know how to confirm that the inverter pump is functioning correctly? If it isn't, I would suppose that the inverters could get too warm in the 5-10 minute run window. Certainly not the MGs.

The second 'no-start' does sound like a weak 12 v, but I reckon that you have already made that good.

If you do get the DTCs, a quite complete interpretation of them is here:

http://www.ecrostech.com/Products/Mi...UserManual.pdf

Please post any progress, and good luck!

[whmracer99]

<div class='quotetop'>QUOTE(hobbit @ Aug 31 2007, 10:20 AM) [snapback]504857[/snapback]</div>

The codes, particularly those stored at the time of the xmas-tree
failure, are the most important thing. Simply parts-swapping is
the blind bumbling way to go at it as you've said, and most dealer
shops aren't actually interested in a point diagnosis. With minor
front-end damage you might be looking at bum wiring harness or
connector parts, but in some critical control location. How about
the low-voltage wires that run down the front of the engine and
split out to the transaxle? Are they in good shape? Did you pull
all the connectors and look at 'em [which can have the effect of
reseating a questionable connection sometimes too]? Are the HV
wires actually dinged at all, or anything coming off the inverter?
Does the engine idle stably in neutral once the car starts? Is it
normally driveable in the time before the codes light up? Do you
have a scantool of any sort such that you can pull your own codes
even if you can't necessarily see their meaning right away [i.e.
can look them up online]?
.
_H*
[/b]

I don't have the codes with me (unfortunately) but I do have a decent Genisys scanner for pulling the codes and doing resets. I should get the car back from the dealer and will try and recreate the failure and get you the codes over the next couple of days.

I will go back and examine the low voltage wiring and connectors in front of the motor and I also want to recheck the high voltage connections at the traction battery. The HV wires did have a slight cut on them where they entered the invertor so that's why the dealer required they be replaced.

Once started, the engine idle wandered for a short time and then settled which I credited to the engine computer having to go through the relearn process after having power removed from the computer and a new throttle body being installed. When the car was driving it appeared to drive normally (just a couple of quick laps around my subdivision) with the gas engine staying running. It continued to drive after the warning lights lit up on the gas engine but from that point forward it would not start once the gas engine was turned off and would not engage the traction motor to move the car via the electric motor.

My experience with regular vehicles would steer me towards a loose connnection somewhere since there is a click and sometimes a slight engine rotation when the key is in "start".

If you have any other questions let me know.

thanx.

[whmracer99]

Just to add some additional detail (I'm trying not to make this into a book but trying to supply the info you need at the same time) originally when we got the car started it did have codes for the oil control valve failure and gas engine power too low before we changed the throttle body and oil control valve. There was also no throttle response.

After changing those two items and the invertor and having the engine start the engine power code (engine running) and oil control valve codes didn't come back and the engine rpm did change with throttle application. From my memory it does now show the other engine power code (that goes with the engine no start).

I've seen a couple of posts on cleaning the buss bars on the big battery. Is there a prefered method for getting the corrosion removed??

[hobbit]

Well, heck, if it turns into a book with a good conclusion and clear
info at the end, that can't hurt! Any knowledge improvement is good.
.
_H*

[whmracer99]

Well, the car came back from the dealer today and the story gets a little stranger.

When the car rolled off the wrecker the 12v battery was dead so I hooked up a jump box and POOF the car started right up. The idle was a little unstable but otherwise everything looked and sounded OK.

I put the car in reverse and it pulled backwords and it pulled forward in drive so I started to drive it and everything sounded/felt/looked fine for the first 20 feet or so. The engine responded to the accelerator pedal and the car pulled away fine. At about 20 feet the warning tree lit up and the main battery indicator and check engine light lit at the same time. The car lost power and gradually stopped responding to the accelerator pedal entirely. The main display started flickering on and off and the PRNDB transmission display lost it's indicator although the letters stayed lit.

The gas engine stayed running and the only noise I heard that sounded out of place was a light rattling from the front when the car tried to move.

Of course, after I shut the car off it wouldn't restart. The Christmas tree and the main battery warning light both flash when the car is turned to the on position and nothing happens when the key is turned to start other than the main display goes out and then comes back on when the key is turned back to the ON position.

Unfortunately, even though the check engine light was lit my scanner showed no codes that were current or historical.

I have the power leads taken off the 12v battery to see if it will restart after it sits dead for awhile but I'm not sure what that proves either way.

Any suggestions would be helpful -- thanks!!

[hobbit]

Sounds like your 12V DC/DC converter ain't working, and the battery
is close to flat. Hang a voltmeter off your 12V bus and go through
the same tests. If you don't see a jump up to 13.8 or 14 when the
system comes to READY, you've got a charging problem.
.
_H*