Check engine light?

Tiny
2CP-ARCHIVES
  • MEMBER
  • 1995 PONTIAC GRAND AM
  • 4 CYL
  • FWD
  • AUTOMATIC
  • 109,994 MILES
1995 Pontiac Grand Am mileage: 110,000. What might cause the check engine light to come on when you are driving at highway speed and then let off the gas? You can drive for varying distances, but the first time you let off the gas the CEL comes on. If you decelerate (close the throttle) very slowly you can keep the light from coming on. I want to try to check the codes but the printout on the connector under the steering wheel doesn't match other diagrams I've seen. As you look at it from the drivers seat, it has two rows of six pins. There is one pin in the top right of the connector and two pins in the lower right of the connector. The connector alignment tab is on the top. This would equate to pins A, K, & L from other diagrams I've seen.
Do you
have the same problem?
Yes
No
Wednesday, October 20th, 2010 AT 9:24 PM

28 Replies

Tiny
2CP-ARCHIVES
  • MEMBER
  • 4,544 POSTS
On pre-1995 cars you could jump between two of the pins and read the codes that were stored in the computer. 1995 and newer cars require the use of the OBDII scanner to retrieve the codes.

This guide will show you how

https://www.2carpros.com/articles/buick-cadillac-chevy-gmc-oldsmobile-pontiac-gm-1983-1995-obd1-code-definitions-and-retrieval-method

Please run down this guide and report back.
Was this
answer
helpful?
Yes
No
Wednesday, October 20th, 2010 AT 9:26 PM
Tiny
JOHNHOCHSCHILD
  • MEMBER
  • 1 POST
  • 1995 PONTIAC GRAND AM
  • 4 CYL
  • FWD
  • AUTOMATIC
  • 140,000 MILES
Hi I am a mechanic, im working on this car for a friend and its runs decent but it is running way too rich on the second cylinder from the drivers side, pulled all the plugs and they were ALL golden brown but the one was wet, so I replaced all the plugs anyways, and replaced a bad vaccum line, changed the oil, changed the fuel filter, and ran injector cleaner thru it, did the ear check with a screw driver to each injector and all seem to be working just fine, took the car for a test drive and when I dropped it into first and florred it, it hit a little over 30 and sounded like it was hitting a rev limiter but it wasnt, and at the same time the coolent light and check engine light would flash back and fourth PLZ help! Its a 2.3 liter quad DOHC 16 valve
Was this
answer
helpful?
Yes
No
Monday, July 6th, 2020 AT 7:08 PM (Merged)
Tiny
MMPRINCE4000
  • MECHANIC
  • 8,549 POSTS
Start by scanning the PCM for codes. A malfunctioning coolant sensor will cause a rich fuel mixture.

On an OBDI system, short A and B in diagnostic link and count flashes.
Was this
answer
helpful?
Yes
No
Monday, July 6th, 2020 AT 7:08 PM (Merged)
Tiny
PITMUNK
  • MEMBER
  • 1 POST
  • 1995 PONTIAC GRAND AM
  • 4 CYL
  • FWD
  • MANUAL
  • 242,000 MILES
My 1995 grand am 2.3l quad 4 runs great at idle but under load or quick acceleration stumbles I have changed the coils the fuel filter and checked the gap on plugs (0.060) and changed the o2 got code from snapon scan tool #55 could this be a bad ground? Did notice the ground for the ecm needed to be cleaned up
Was this
answer
helpful?
Yes
No
Monday, July 6th, 2020 AT 7:08 PM (Merged)
Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
1995 Pontiac Grand Am car stumbiling

Dirty fuel injectors (cleaning the injectors often fixes this).
Bad MAP (manifold absolute pressure) sensor
Bad TPS (throttle position) sensor
Bad or dirty MAF (mass airflow) sensor
Low fuel pressure (leaky fuel pressure regulator or weak fuel pump)
Vacuum leaks (intake manifold, vacuum hoses, throttle body, EGR valve)
Bad gasoline (fuel contaminated with water or too much alcohol)

Sometimes, what feels like a hesitation is actually ignition misfire rather than lean misfire. The causes of ignition misfire may include:

Dirty or worn spark plugs
Bad plug wires
Weak ignition coil
Wet plug wires
Was this
answer
helpful?
Yes
No
Monday, July 6th, 2020 AT 7:08 PM (Merged)
Tiny
AGON813
  • MEMBER
  • 12 POSTS
  • 1994 PONTIAC GRAND AM
  • 4 CYL
  • FWD
  • AUTOMATIC
  • 112,000 MILES
Hello. I have a problem with my car. The check engine light comes on and I had a scanner put on it. The scanner came up with a fault code for the O2 sensor, open circuit. So I cut the wire and spliced it and made a new connection. Then I tested the voltage into the ecm and the voltage is only fluctuating between.1 and.2 volts, and even before I spliced it, I also tested it and it was the same, when it sould be between.4 and.5. I also bought a new 02 sensor and it still has the fault for an open 02 circuit. Please can you help me!
Was this
answer
helpful?
Yes
No
Monday, July 6th, 2020 AT 7:18 PM (Merged)
Tiny
DOCFIXIT
  • MECHANIC
  • 18,828 POSTS
Was it code 13? The wire you cut is it still in circuit? Did you ohm out ground on ECM? Let me know
Was this
answer
helpful?
Yes
No
Monday, July 6th, 2020 AT 7:18 PM (Merged)
Tiny
AGON813
  • MEMBER
  • 12 POSTS
Yes the code is 13. I also tested the ground and it is good. I spliced the wire under the hood near where the harness goes into the ecm and it is still in the circuit.
Was this
answer
helpful?
Yes
No
Monday, July 6th, 2020 AT 7:18 PM (Merged)
Tiny
JERBEAR1969
  • MEMBER
  • 1 POST
  • 1994 PONTIAC GRAND AM
  • 2.3L
  • 4 CYL
  • FWD
  • AUTOMATIC
  • 78,000 MILES
I have a 1994 Pontiac grand am 4 cyclinder and engine light is on. I looked up how to test the obd but nothing is working. The connector only has 3 pins. 2 pins on top left and 1 pin bottom left.
How do I go about testing it. It does not have any other pins just the 3 on left side of connector
If need a picture I can get that
Thank s very much
Was this
answer
helpful?
Yes
No
Monday, July 6th, 2020 AT 7:18 PM (Merged)
Tiny
CARADIODOC
  • MECHANIC
  • 33,699 POSTS
On '95 and older GM products there will always be only one corner of the connector that has two wires right next to each other. Those are the two to connect to read the diagnostic fault codes.

Go to this page for the full instructions:

https://www.2carpros.com/articles/buick-cadillac-chevy-gmc-oldsmobile-pontiac-gm-1983-1995-obd1-code-definitions-and-retrieval-method
Was this
answer
helpful?
Yes
No
Monday, July 6th, 2020 AT 7:18 PM (Merged)
Tiny
KEVINATK
  • MEMBER
  • 1 POST
  • 1994 PONTIAC GRAND AM
Engine Performance problem
1994 Pontiac Grand Am 6 cyl Two Wheel Drive Automatic

while driving after about an hour the check engine light comes on there are no other problems the car runs fine I have driven it several times the past owner said there were no problems with car the car starts up very well afte I turn off car the light goes off and dnt come on agian till im driving agian after about an hour later
Was this
answer
helpful?
Yes
No
Monday, July 6th, 2020 AT 7:18 PM (Merged)
Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
Check engine light coming On

Have the computer scanned for code/s-you have a problem within the engine management system that caused the CEL to turn on-This is your starting point of diagnosis, finding out what's going on
Was this
answer
helpful?
Yes
No
Monday, July 6th, 2020 AT 7:19 PM (Merged)
Tiny
CASE28
  • MEMBER
  • 7 POSTS
  • 1993 PONTIAC GRAND AM
1993 Pontiac Grand Am SE V6 3.3L mileage: 157,000
Hello everyone this problem has started when I bought the car it was sold as is. I just bought it one month ago at a used car lot. The problem is when im driving or the engine is cold the check oil light & the service engine light with the check gauges light come on & blink. The oil gauge is at 120psi when its cold but it goes down when it starts to get warm. I have given the car a tune up myself. I took it to a mechanic he couldn't figure out what the problem was. I then took it to one of my brothers who knows alot about cars to. We removed the oil sending unit and the oil level sensor that goes to the oil pan. Replaced them with new ones. That stopped the light for a few days but it keeps on coming on now. I know the car is at level with the oil & its not heating up im just so frustrated with this I have no idea who to ask anymore.? I would really appreciate some help with this im totally clueless.
Was this
answer
helpful?
Yes
No
Monday, July 6th, 2020 AT 7:19 PM (Merged)
Tiny
CASE28
  • MEMBER
  • 7 POSTS
Update

Their were two problems

1st Problem: Bad Cluster
Check Oil Light + Check Gauges Light

2nd Problem: Engine Vacume Leak
Service Engine Light
Was this
answer
helpful?
Yes
No
Monday, July 6th, 2020 AT 7:19 PM (Merged)
Tiny
GRANDAMOWNER
  • MEMBER
  • 1 POST
  • 1992 PONTIAC GRAND AM
  • 4 CYL
  • FWD
  • AUTOMATIC
  • 75,000 MILES
Check engine soon light
Was this
answer
helpful?
Yes
No
Monday, July 6th, 2020 AT 7:19 PM (Merged)
Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
Check engine light on

Have the computer scanned for code/s-you have a problem within the engine management system that caused the CEL to turn on-This is your starting point of diagnosis, finding out what's going on
Was this
answer
helpful?
Yes
No
Monday, July 6th, 2020 AT 7:19 PM (Merged)
Tiny
JARED575
  • MEMBER
  • 10 POSTS
  • 1991 PONTIAC GRAND AM
  • 4 CYL
  • FWD
  • AUTOMATIC
  • 90,000 MILES
Hi, my grand am, when I start the car "normally" the check engine light comes on and the engie idles really slowly and heavily, ie the car rumbles and can shake for a minute, after idling for a minute the engine speed will level off and sound more normal however when I go to press on the gas pedal and drive off the engine hesetates and drives like a tank, there is clearly no power and the engine will heat up very quickly but won't overheat. Now I had the engine tuned up at my local midas, "level 2 service" according to the bill which they said should fix it. It worked for a week. They said whent hey scanned the computer they were getting a "long cranking code error" now whe I took it back tehy rescanned and said it was the same error and it was most likely becasue the car was old. This was about 1 year ago, Now I recently learned that if I crank the engine for a minute but don't allow it to start, then wait for the lights and stuff to shut off and then recrank the engine it starts very quickly with no check engine light. Also if I am driving and the check engine light came on at startup that if I get to 60km/h I can pull a fuse, top eft I think it's labelled ECM, wait 5 seconds while costing the engine sounds like it stalls the speedometer drops to zero and the check engine light flickers, once I plug it back in the engine starts running and everyhting comes back on and the engine runs wonderfully. Now I was wondering what is causing this, it's a new starter, new spark plugs(not sure about the spark plug wires) but what I can't figure out is why it does this, is it the computer? I bought a a reader, I turn the car to on but don't start it and the check engine light blinks out the codes that are stored, I get code 42 all the time and once and a while code 33, right now that one isn't there jsut 42. Thanks for any help!
Was this
answer
helpful?
Yes
No
Monday, July 6th, 2020 AT 7:20 PM (Merged)
Tiny
KHLOW2008
  • MECHANIC
  • 41,815 POSTS
Hi jared575,

Thank you for the donation.

Is this a 2.3 L or 2.5 L engine?

There are various different specifications and the correct one is needed for accurate diagnosis.

Code 33 is the MAP sensor circuit.

Code 42 is for EST (Electronic spark Timing) circuit.

The VIN would help in determining the system used.
Was this
answer
helpful?
Yes
No
Monday, July 6th, 2020 AT 7:20 PM (Merged)
Tiny
JARED575
  • MEMBER
  • 10 POSTS
The vin, which i'm assuming is the vehicle identification number is 1g2ne54u3mc510398 it's a 2.5L LE model 91 pontiac grand am.
Was this
answer
helpful?
Yes
No
Monday, July 6th, 2020 AT 7:20 PM (Merged)
Tiny
KHLOW2008
  • MECHANIC
  • 41,815 POSTS
Yes VIN is Vehicle Identification Number. You are able to provide the details so here are the description and diagnostic procedure.

CODE 42, EST CIRCUIT OPEN OR GROUNDED

Code 42 indicates the ECM has seen an open or short to ground in HEI EST or by-pass circuit.

NOTE: Test numbers refer to test numbers on diagnostic chart.

1. This test confirms Code 42 and determines if fault is a hard failure or intermittent condition.

2. This test checks for a normal EST ground path through the ignition module. If EST circuit is shorted to ground, reading will be less than 500 ohms.

3. As test light voltage touches by-pass circuit, the module should switch. This will cause the ohmmeter to switch from hundreds of ohms to thousands of ohms. This test assures that the module "switched".

4. If module did not switch, this step will test for a short in circuit No. 423, an open in circuit No. 424, and a faulty ignition module connection or module.

5. This step confirms that Code 42 is a faulty ECM and not an intermittent problem in circuits


https://www.2carpros.com/forum/automotive_pictures/192750_Code42EST91GrandAmLE_1.jpg



https://www.2carpros.com/forum/automotive_pictures/192750_Code42EST91GrandAmLE01_2.jpg



https://www.2carpros.com/forum/automotive_pictures/192750_Code42EST91GrandAmLE02_1.jpg

Was this
answer
helpful?
Yes
No
Monday, July 6th, 2020 AT 7:20 PM (Merged)

Please login or register to post a reply.

Sponsored links