diagnostic test/service engine light question
Thread Starter
Senior Member
Joined: Nov 2001
Posts: 827
Likes: 0
From: Tenino, Washington
Car: 89 f-bird and some others
Engine: 3.4
Transmission: 700R4
Axle/Gears: 3.42
diagnostic test/service engine light question
My service engine light has been coming on lately when driving slowly up a gentle slope and when cruising about 70-80 on the autobahn. When the hill levels off and I let up on the gas a litlle, the light goes off. On the autobahn it just comes on for awhile no matter if I stay on the gas or let up. This happened tonight and my friend were freaking out thinking I was going to break down. ha ha, little did they know this happens all the time. anyway before I fall asleep on my keyboard, If I get it hooked up, will the fault still show up even if the S-E light if off, or does that light need to be on for the diagnostic program to read the fault. Cuz I'm sure when they test it the service engine litgh will be off.
Supreme Member
Joined: Mar 2000
Posts: 13,414
Likes: 6
From: Central NJ, USA
Car: 1986 Firebird
Engine: 2.8 V6
Transmission: 700R4
When "they" test it? Who is "they"?? I think you should test it. Here's something I just typed up:
And yes, the ECM will store trouble codes for a while. They disappear after a certain internal... something like "after 500 starts of the engine and no repeated code". I've heard mechanics say "oh, well, if the SES light isn't on now, I can't diagnose it, if you get the light to stay on, come back"- but I think they just didn't want the job.
Originally posted by TomP
You could search "check for codes" in the V6 forum (click on upper right hand of this screen, there's a search button).
Basically, look at your ALDL connector, below the steering wheel. Remove the rectangular cover. There's two rows of pins there; ignore the bottom row completely. On the UPPER row, look at the RIGHTMOST two pins.
With the car off, put a paperclip or piece of wire in the ALDL so you connect the RIGHTMOST two pins in the UPPER row.
Turn the key from "off" to "run/test lights" position- the position right before you would crank the engine. DO NOT CRANK THE ENGINE!!! You'll see your SES light up, and hear your electric fan come on.
The SES light will start to blink codes at you. It blinks each code 3 times. It always (well, it should always) start with code 12- "no distributor reference pulses". This is normal, because hey, the engine isn't running!
Code 12 is shown like this: Flash, pause, flash flash
An example of code 35 would be flash flash flash, pause, flash flash flash flash flash. Remember each code repeats three times. When there are no more codes, the ECM starts over, and will start flashing code 12 (and the rest of your codes) over again. If you have no codes, all you'll see is code 12.
Turn the key to OFF, and THEN, remove the jumper wire from the ALDL.
This info is also in the "3rd gen FAQ" in the "Miscellaneous" (last) section. Find it thru thirdgen.org's main page.
You could search "check for codes" in the V6 forum (click on upper right hand of this screen, there's a search button).
Basically, look at your ALDL connector, below the steering wheel. Remove the rectangular cover. There's two rows of pins there; ignore the bottom row completely. On the UPPER row, look at the RIGHTMOST two pins.
With the car off, put a paperclip or piece of wire in the ALDL so you connect the RIGHTMOST two pins in the UPPER row.
Turn the key from "off" to "run/test lights" position- the position right before you would crank the engine. DO NOT CRANK THE ENGINE!!! You'll see your SES light up, and hear your electric fan come on.
The SES light will start to blink codes at you. It blinks each code 3 times. It always (well, it should always) start with code 12- "no distributor reference pulses". This is normal, because hey, the engine isn't running!
Code 12 is shown like this: Flash, pause, flash flash
An example of code 35 would be flash flash flash, pause, flash flash flash flash flash. Remember each code repeats three times. When there are no more codes, the ECM starts over, and will start flashing code 12 (and the rest of your codes) over again. If you have no codes, all you'll see is code 12.
Turn the key to OFF, and THEN, remove the jumper wire from the ALDL.
This info is also in the "3rd gen FAQ" in the "Miscellaneous" (last) section. Find it thru thirdgen.org's main page.
Junior Member
Joined: Dec 2001
Posts: 69
Likes: 0
From: Toledo Ohio
My 1990 3.1 did that for awhile, turned out to be the knock sensor setting off the code. Its goes out but is stored till i think you reset the computer(by disconecting the batter for 5 minutes). The knock sensor is easy to replace, also called Electronic spark control sensor i think. Try using a mid grade gas, i was told that more then likely will cause your car to do this, once you pick and octane level stick with it, dont jump around.
Thread
Thread Starter
Forum
Replies
Last Post
