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1999 Corolla Computer Problem?


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#1 ncg

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Posted 02 January 2007 - 09:57 PM

Hello! I am very new to this land/board. I searched for other threads, but failed to find any about similar issues.

I left my 1999 Corolla(120k miles) at the airport for 6 days in freezing weather. When I returned I drove home without incident. The next morning, as I was about to get a bite to eat the car died about 100 yards from my driveway. Turning the key would crank the starter, but nothing happened in the engine. I checked the oil, it was lower than the last dot so I put some more in, and I checked fuses. Still baffled, I checked the return fuel line to see if any fuel was coming out of the engine. There wasn't any trace of fuel, so I thought maybe it was the fuel pump. Apparently for the 1999 the fuel filter is bundled with the pump.
I then brought the car into a mechanic who spent a few hours tracking down the problem, eventually saying it is an electrical problem and that he is 95% sure it needs a new computer. I am assuming he means the engine control computer.

Has anyone had a computer go bad on them? Have they experienced a similar situation where the car suddenly dies? The car really hadn't warmed up (still freezing weather) before I drove it. It seems so odd that I got home fine from the airport the night before, only to have it die the next morning!


The shop quoted me $300 for a used computer and $1200 for a new one. I found a salvaged one on ebay for $100. We are waiting for it to arrive. Do the quoted prices seem reasonable?

Edited by ncg, 03 January 2007 - 09:20 AM.

#2 Bitter

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Posted 02 January 2007 - 10:02 PM

hmm thats odd, sure its not a bad relay or the fuel pump itself?

#3 matty10354

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Posted 02 January 2007 - 10:36 PM

i agree with bitter. bad ecu sounds off. i would investigate some more. i would rule out the days old cold having anything to do with it if you drove it that night ok it wouldnt make sense that the computer would quit the next day

#4 Bikeman982

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Posted 03 January 2007 - 12:02 AM

My daughter's car stopped when she was driving it and it turned out to be her timing belt had broken.
I have changed fuel pumps and they are easy to do, if that is the problem.
I have also changed many ECU's and they are very easy to change, but it does not sound like that would be the source of your cars problem.
The prices sound about right, although I have bought ECU's from salvage yards for less money.

Edited by Bikeman982, 03 January 2007 - 09:49 PM.

#5 ncg

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Posted 03 January 2007 - 09:03 AM

I thought it may have been the fuel pump, but it didnt make a difference. The mechanic friend said it was an "electrical problem". Whatever that means.

Now a bad relay may the culprit. I visual inspection of the fuses didn't bring to light anything. I couldn't check the relays and will give that a shot.

hmm thats odd, sure its not a bad relay or the fuel pump itself?


#6 ncg

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Posted 03 January 2007 - 09:05 AM

My daughter's car stopped when she was drivin it and it turned out to be her timing belt had broken.
I have changed fuel pumps and they are easy to do, if that is the problem.
I have also changed many ECU's and they are very easy to change, but it does not sound like that would be the source of your cars problem.
The prices sound about right, although I have bought ECU's from salvage yards for less money.


I had checked the timing belt, and no problems there. I'll let y'all know what we find.

#7 fishexpo101

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Posted 03 January 2007 - 10:36 AM

Well, on the 8th gen Corollas - there is no return fuel line and no timing belt. Instead - they use a returnless fuel system and timing chain. It is not unusual to find the fuel log to be empty when the car is off for some time - the fuel regulator and pump will only supply the engine with gas that it needs dynamically. Not being picky - just extra information. Since I've seen quite a few people get taken by some unscrupulous mechanics that their car needs a new timing belt every 60K miles, when in fact they have a timing chain and needs no regular maintenance in normal conditions.

Though it is not very common - engine ECU can die for any number of reasons - I would only say there is an ECU problem if every other avenue has been explored. I would start looking into the EVAP system first - as this is a weak point in the 8th gen. I assume that the mechanic has ruled out a fuel pump issue (did he say how he verified this?). If the fuel pump is fine - then start looking at the ignition system (coil packs, wires, plugs, sensors). You have two coil packs (each supports two plugs - a waste spark system, ie. plug will fire at the bottom of the compression and exhaust strokes) - I would verify that you have spark. Easy way to do this is to just short the plug wire to ground and crank the engine over. You should see a spark. They also make an in-line pluggable lamp that also does the same thing, just more elegantly than the shorting method. If you do not see a spark - then you probably have a disconnect somewhere around the crankshaft and camshaft position sensors. They run to the ECU and provide information on where the valves and pistons are at to determine when to fire. If all that looks good - then you increase the probability of having an ECU problem.

Some relays have a little hole on the bottom that has to be pressed in to reset the relay (sort of like a circuit breaker). Other relays are hidden below and out of sight - though most of what you need to check should be easily accessible. This engine is also very sensitive to having good chassis grounds. A loose ground or a weak ground can generate electrical noise that can confuse the engine computer or even damage it. You would have to pickup a factory service manual to double check these yourself - a good mechanic will cover this early on. Good Luck.

#8 Bikeman982

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Posted 03 January 2007 - 09:53 PM

Has your part arrived from e-Bay? You can change it and see if that really is the source of the problem.

#9 MatrixTech

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Posted 03 January 2007 - 10:30 PM

Has your part arrived from e-Bay? You can change it and see if that really is the source of the problem.

circuit open relay??? c/opn is how its labeled swap or replace it and try it that runs the fuel pump.