Trick for reading codes on a 1985
Thread Starter
Safety Car
Joined: Nov 2001
Posts: 3,753
Likes: 191
From: Orange County California
Trick for reading codes on a 1985
I used to know how to do this but lost the info. How to you tap into the ALDL to read the light to know why you have a check engine light on in a 1985
Race Director
Joined: Dec 2000
Posts: 17,551
Likes: 26
From: El Paso Texas
Jump terminals A and B on the ALDL
Turn the key on but don't start the car.
Watch the Check Engine Light flash.
You should get 3 "12" codes at the beginning, then any stored Diagnostic Trouble Codes, then 3 "12" codes at the end.
A "12" code would be as follows: Flash, pause, flash flash....followed by a long pause. That will repeat 3 times. Then for example, if you had a "34" codes stored, it would be: flash flash flash, pause, flash flash flash flash.
Damn....I'm sure getting tired of all this flashing.
Good luck.
Turn the key on but don't start the car.
Watch the Check Engine Light flash.
You should get 3 "12" codes at the beginning, then any stored Diagnostic Trouble Codes, then 3 "12" codes at the end.
A "12" code would be as follows: Flash, pause, flash flash....followed by a long pause. That will repeat 3 times. Then for example, if you had a "34" codes stored, it would be: flash flash flash, pause, flash flash flash flash.
Damn....I'm sure getting tired of all this flashing.
Good luck.
Race Director
Joined: Dec 2000
Posts: 17,551
Likes: 26
From: El Paso Texas
The factory service manual has them, as does the Haynes manual. Here's a web site that outlines the procedure, has the codes (page 4 & 5) and gives you an idea where to start looking for each code.
Diagnostic Trouble Codes.
Hope this helps. Just remember that just because a particular code is set doesn't mean the corresponding sensor has failed. Always test your parts before replacing, and check all associated wiring, harness connections, etc. before condemning the sensor. Nothing sucks worse than spending $100 for a part that can't be returned only to discover that it was a faulty connection at a harness causing the problem. And if it's a throttle position sensor, always try adjusting the sensor and resetting the code before replacing it.
Good luck.
Diagnostic Trouble Codes.
Hope this helps. Just remember that just because a particular code is set doesn't mean the corresponding sensor has failed. Always test your parts before replacing, and check all associated wiring, harness connections, etc. before condemning the sensor. Nothing sucks worse than spending $100 for a part that can't be returned only to discover that it was a faulty connection at a harness causing the problem. And if it's a throttle position sensor, always try adjusting the sensor and resetting the code before replacing it.
Good luck.
Heel & Toe
Joined: May 2021
Posts: 15
Likes: 0
From: Sarasota, FL
perpetual blinking
Thanks for the help!
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Team Owner
Joined: Jul 2004
Posts: 28,501
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From: Hartford WI
Heel & Toe
Joined: May 2021
Posts: 15
Likes: 0
From: Sarasota, FL
Thank you, gents!
I guess I need to diagnose using another method then. I've been trying to find info on the forum, but I have been going down a lot of rabbit holes.
It is a recent purchase, so I do not have a baseline for comparison, but it starts slow, blows smoke on startup, and exhibits generally rough performance.
I guess I need to diagnose using another method then. I've been trying to find info on the forum, but I have been going down a lot of rabbit holes.
It is a recent purchase, so I do not have a baseline for comparison, but it starts slow, blows smoke on startup, and exhibits generally rough performance.
Team Owner
Joined: Aug 2004
Posts: 21,543
Likes: 3,216
From: Park City Utah
Team Owner
Joined: Aug 2004
Posts: 21,543
Likes: 3,216
From: Park City Utah
You could do a visual on the injectors by pulling the fuel rail, leave it hooked up, crank the engine and watch them all fire. Look for same-looking, nice symmetrical cones of spray.
You can also buy a tool that fires each injector for a specific period of time, you watch the fuel pressure drop to see flow rate of each injector. This test doesn't confirm spray pattern/quality.
You can also buy a tool that fires each injector for a specific period of time, you watch the fuel pressure drop to see flow rate of each injector. This test doesn't confirm spray pattern/quality.
Team Owner
Joined: Jul 2004
Posts: 28,501
Likes: 3,302
From: Hartford WI
You could do a visual on the injectors by pulling the fuel rail, leave it hooked up, crank the engine and watch them all fire. Look for same-looking, nice symmetrical cones of spray.
You can also buy a tool that fires each injector for a specific period of time, you watch the fuel pressure drop to see flow rate of each injector. This test doesn't confirm spray pattern/quality.
You can also buy a tool that fires each injector for a specific period of time, you watch the fuel pressure drop to see flow rate of each injector. This test doesn't confirm spray pattern/quality.
Team Owner
Joined: Aug 2004
Posts: 21,543
Likes: 3,216
From: Park City Utah
