1990 Ford Taurus Check Engine Light
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1990 Ford Taurus Check Engine Light
Hi,
I observed the check engine light flicker and used a code reader to extract 2 continuous errors:
1) 39 Automatic overdrive not operating properly (transmission failure)
2) 63 Throttle Position (TP) circuit fault, below minimum voltage
I then ran the KOER tests to make sure there were no issues there and I got a:
3) 25 Knock not sensed during Dynamic Response Test
Do any of you know how I can fix an error 25? I hope that by fixing that the other 2 might go away.
If an error 25 is not a big deal - what sensors would be reporting a 39 and 63? Maybe the errors are being caused by a loose wire or damaged sensor?
Any advice would be enormously appreciated - Thanks very much!
Daragh Hartnett
I observed the check engine light flicker and used a code reader to extract 2 continuous errors:
1) 39 Automatic overdrive not operating properly (transmission failure)
2) 63 Throttle Position (TP) circuit fault, below minimum voltage
I then ran the KOER tests to make sure there were no issues there and I got a:
3) 25 Knock not sensed during Dynamic Response Test
Do any of you know how I can fix an error 25? I hope that by fixing that the other 2 might go away.
If an error 25 is not a big deal - what sensors would be reporting a 39 and 63? Maybe the errors are being caused by a loose wire or damaged sensor?
Any advice would be enormously appreciated - Thanks very much!
Daragh Hartnett
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Joined: Jan 2003
Posts: 9,748
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From: Connecticut
Hi Daragh, welcome to FTE!
You should start with the Throttle Position Sensor (TPS) code first. That is one of the most important sensors on the vehicle, and it could have a bearing on the way your tranny behaves.
If you want to test the TPS, you can use this as a guide:
http://fordfuelinjection.com/tps.html
but it sounds to me like either the TPS is shot, or you have a problem with the circuit (ground or open due to chafed wire, for example).
Your motor doesn't have a knock sensor, so that code can be ignored.
You should start with the Throttle Position Sensor (TPS) code first. That is one of the most important sensors on the vehicle, and it could have a bearing on the way your tranny behaves.
If you want to test the TPS, you can use this as a guide:
http://fordfuelinjection.com/tps.html
but it sounds to me like either the TPS is shot, or you have a problem with the circuit (ground or open due to chafed wire, for example).
Your motor doesn't have a knock sensor, so that code can be ignored.
Logistics Pro
Joined: Jan 2002
Posts: 4,907
Likes: 39
From: suburban atlanta
The 25 is caused by testor error. You are spozta floor the gas pedal and tap the brake pedal, and wiggle the steering wheel after getting all the stored codes. The flooring will cause knock sensor to send a code if you have one, the brake pedal will set the BOO code if applicable, and the steering wheel is looking for the TSPS to tell the ECM the power steering load is imminent. Now, these actions are only for specific cars, so don't take this a a fault on you.
The TPS can really futz things up, though. If you have a tach, and the engine rpm changes 2-300 rpm while cruising, you may have a bad TPS. The ECM 'thinks' you just closed the throttle, (or floored it...) and drops you out of OD. If the TPS has dropout, it can cause that problem. Mine did, about 10 years ago. It 'tested' fine using a tester, but using an analog VOM, you could see the dropout. Replaced, and all has been well.
good luck
tom
The TPS can really futz things up, though. If you have a tach, and the engine rpm changes 2-300 rpm while cruising, you may have a bad TPS. The ECM 'thinks' you just closed the throttle, (or floored it...) and drops you out of OD. If the TPS has dropout, it can cause that problem. Mine did, about 10 years ago. It 'tested' fine using a tester, but using an analog VOM, you could see the dropout. Replaced, and all has been well.
good luck
tom
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Rockledge & Tomw, thanks very much for the responses. The night before last I decided to take a gamble and swap out the TPS - since then the check engine light has not come on so I think that was it! WOO HOO!!!
Tomw, when performing the KOER test I do turn and hold the steering wheel and then tap the brake (and both of these tests pass) but when I floor the accelerator at the correct time I still get the 25 error - I think Rockledge is correct - there is probably no Knock sensor on the 1990 Ford Taurus GL 3.0 - however, autozone lists one.....
Again - thank you both for your input - I would not have solved this one without yer help,
Daragh
Tomw, when performing the KOER test I do turn and hold the steering wheel and then tap the brake (and both of these tests pass) but when I floor the accelerator at the correct time I still get the 25 error - I think Rockledge is correct - there is probably no Knock sensor on the 1990 Ford Taurus GL 3.0 - however, autozone lists one.....
Again - thank you both for your input - I would not have solved this one without yer help,
Daragh
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