1984 Corvette Check engine light
Thread Starter
Instructor
Joined: Sep 2005
Posts: 173
Likes: 0
From: St. Louis MO
1984 Corvette Check engine light
I just bought the car and its doing some weird things. Even with a plug wire off the Check engine light does not come on.
when you turn your key to on (not starting the car), and it normally does a bulb check, should the check engine light light up?
Is the check engine light on the digital dash? or more towards the center display area where the security / hatch ajar lights are?
Is it the engine computer that controls the check engine light?
I have checked all of the bulbs in the center area, they all look good. and the digital dash works fine.
I have also jumpered the 2 pins on the obd interface, then turned the key on, i get no codes (book says i should get a code 12.)
I dont know how you feel about driving a car when the check engine light doesnt come on. Personally it scares the heck out of me.
Any advice greatly appreciated, and i am all ears
when you turn your key to on (not starting the car), and it normally does a bulb check, should the check engine light light up?
Is the check engine light on the digital dash? or more towards the center display area where the security / hatch ajar lights are?
Is it the engine computer that controls the check engine light?
I have checked all of the bulbs in the center area, they all look good. and the digital dash works fine.
I have also jumpered the 2 pins on the obd interface, then turned the key on, i get no codes (book says i should get a code 12.)
I dont know how you feel about driving a car when the check engine light doesnt come on. Personally it scares the heck out of me.
Any advice greatly appreciated, and i am all ears
Melting Slicks
Joined: Jun 2004
Posts: 3,032
Likes: 4
With no check engine light my helms manual tells me it's going to either be the bulb, or the ECM. You might want to find your own factory service manual if you're planning on doing your own work - you can find them fairly cheaply on ebay.
And disconnecting a spark plug wire, shouldn't trip a check engine light, it'll just make the car run like crap.
The 2nd test you did is more appropriate, if you jumpered the A and B ports of the ALDL correctly you should see a check engine light flashing.
And disconnecting a spark plug wire, shouldn't trip a check engine light, it'll just make the car run like crap.
The 2nd test you did is more appropriate, if you jumpered the A and B ports of the ALDL correctly you should see a check engine light flashing.
Intermediate
Joined: Feb 2003
Posts: 28
Likes: 0
From: Cincinnati OH
C 4 1984 check engine
On my '94 with 130k with the key on the center display will show check engine. The check engine is for fuel of emmissions only. Find a good!! vette mech to run the machine check. 
Race Director
Joined: Sep 2000
Posts: 17,298
Likes: 33
From: The Top of Utah
Originally Posted by k0rv3tt389
It is a "Service Engine Soon" light. Same as a Check Engine light. It is on the center console, not the digidash.
RACE ON!!!
Thread Starter
Instructor
Joined: Sep 2005
Posts: 173
Likes: 0
From: St. Louis MO
well i replaced the ecm. (following the helms manual diag instructions.) and fixed the check engine light. Never thought a code 12 could look so good. Took the car out for a spin, and wooohooo it runs awsome compared to what it use to do. That little box was causing most of my problems. Still having a little problem with the fan not kicking on. Trying to decide if i want to replace the relay, or bypass it and make it always on.
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Race Director
Joined: Sep 2000
Posts: 17,298
Likes: 33
From: The Top of Utah
Don't wore it to keep the fan on. With the ignition "ON" pull the wire off of the fan switch. It is located on the passenger side of the engine, screwed into the head between the #6 and #8 spark plugs. Ground that wire. If the fan runs, the fan motor and relay are OK. The fan switch needs replacing. If that doesn't run the fan, temporarily jump 12 volts to the fan motor to test if the motor is good. If the fan runs, do a diagnostic on the relay. Careful, logical, trouble shooting, as outlined in your FSM will save you hundreds of dollars and pay back the cost of the book in time and parts, not wasted.
RACE ON!!!
RACE ON!!!
