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Mitchellman

Check Engine Light, but Can't Pull the Codes

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Hi All,

 

I have a 1994 Buick Regal GS with the 3800(Vin L) and am having some issues retrieving the Codes. It's OBD1, but the 12 pin connector only has A, D, J, and M connectors, so jumping doesn't work. I've tried the Snap On Scan tool at work and it doesn't recognize it's even plugged in. Same with a Bosch Scan tool at Oreillys. I've checked the fuses and all seem to be good.

 

Used to drive the car everyday, and for the past year, I've only been driving maybe once or twice a week. I've noticed a lack of power, and occasionally the check engine light comes on. Mainly in the morning upon first drive after sitting a couple days. My hunch is the Cat is bad, but want to try to get the Codes before I replace it.

 

Thank you!!!

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Yup, 94 & 95 is obd 1.5 and nothing likes it. Sometimes the local dealership runs free code scans. As much as i hate to suggest it, might be best to bring it there if you can't find a tool to read it.

Is it missing or just gutless? Have you checked the obvious things, air filter, spark plugs, etc.? What makes you think it's a bad cat? Not usually the first thing I'd suspect.

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As a fellow 94 owner, 93 was the last year of the paper clip trick. 94 and 95 have OBD2 style codes (Pxxxx) but are still OBD1 with the lack of the universal connector and post cat o2 sensor among other things.

 

You have to get an ALDL cable to scan the car and a laptop to run tunerpro. You would need to also look for a "definition" that contains information specific to your car. The other option is a Tech1 scanner or an expensive used tool that can read 94 and 95 GM computers. They would need to come with multiple cables as GM used different types of connectors in 94 and 95. I think all W bodies used the ALDL connector up until 95 but not sure

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They would need to come with multiple cables as GM used different types of connectors in 94 and 95. I think all W bodies used the ALDL connector up until 95 but not sure

 

12 pin and 16 pin. I know the corvette used an OBD II style in 94 & 95 because they had the 333 PCM and the CamEro/Firebird used the 12 pin in 1994, and the OBD II 16 pin for 1995 despite them having the same PCM both years. If memory serves me some Cadillacs got the OBD II port early and I'm sure there was something else that got it early. At  any rate there were only 2 different ports.

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From what I've read one has to have the proper cartridge for 94-95 GM OBD1.5 scanner & the proper cable connector, the paperclip trick does not work with this particular arrangement & attempting to do so may ruin your ECM.

 

You've definitely got the 12 pin connector?

 

http://shbox.com/1/dlc1.jpg

Yep, definitely the 12 pin.

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I have NO idea why it would be difficult to pull codes on a '94/95 GM vehicle.  It's not like it's a Ferrari or something else exotic and unusual.

 

Any decent scan tool capable of connecting to the ALDL, and having software for the model year should work.

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I have NO idea why it would be difficult to pull codes on a '94/95 GM vehicle.  It's not like it's a Ferrari or something else exotic and unusual.

 

Any decent scan tool capable of connecting to the ALDL, and having software for the model year should work.

 

Because most people are cheap and have this misconception that you can pull codes on any GM OBD1 computer by using a paper clip and jumping connections. That's fine but that specific trick worked up until 93, but since people hear "94" or "95" they automatically think it's the original OBD1 programming with that ability, so when they jam a paper clip in the connector and the light won't blink, they get frustrated and don't know what to do since they hear "scan tool" and think of $1000 snap on scanners, because honestly... scanners are expensive and most folks don't have the amount of cars that warrants that investment since they think they'll only use it once. 

 

Me personally? I need a scanner that can read cars as new as the 2010's but can also deal with OBD1. 

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IIRC, the Actron CP9190 would do what you want, but isn't made any more...I saw one recently at a pawn shop for $70.00, but since I already have several scanners, didn't buy it.

 

Scanners like that, can they pull ABS codes or Airbag codes?

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On a 12 pin DLC pin "B" should be a white wire with a black tracer that is designated as diagnostic request. When we ground that wire to pin "A" which is the black wire with a white tracer and a ground it puts the computer into Diagnostics mode and blinks the codes out on the check engine light. even some cars that have a wire on that pin are incapable of blinking codes on the check engine light

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Yup, 94 & 95 is obd 1.5 and nothing likes it. Sometimes the local dealership runs free code scans. As much as i hate to suggest it, might be best to bring it there if you can't find a tool to read it.

Is it missing or just gutless? Have you checked the obvious things, air filter, spark plugs, etc.? What makes you think it's a bad cat? Not usually the first thing I'd suspect.

It's not missing, and not completely gutless, just kind of sluggish compared to about a year ago. Plugs and wires are good, but 3 years old, and air filter is new. Last winter when it was -30(with wind chill), once the car was warmed up, didn't want to shift properly and wouldn't downshift once in drive. Tranny fluid is not the cleanest(still pink, not brown) and is full. Haven't had that issue since, but car is still sluggish.

 

I plan to do all the works over winter. New plugs, wires, fuel filter, clean injectors and so on.

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Because most people are cheap and have this misconception that you can pull codes on any GM OBD1 computer by using a paper clip and jumping connections. That's fine but that specific trick worked up until 93, but since people hear "94" or "95" they automatically think it's the original OBD1 programming with that ability, so when they jam a paper clip in the connector and the light won't blink, they get frustrated and don't know what to do since they hear "scan tool" and think of $1000 snap on scanners, because honestly... scanners are expensive and most folks don't have the amount of cars that warrants that investment since they think they'll only use it once.

 

Me personally? I need a scanner that can read cars as new as the 2010's but can also deal with OBD1.

I personally don't have a scanner, but at work they have a Snap On Scanner(can't recall the model), but it won't acknowledge my car. Same with the Bosch scanner at Oriellys. Will try to scan it again tomorrow with a different scanner and see what happens.

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I personally don't have a scanner, but at work they have a Snap On Scanner(can't recall the model), but it won't acknowledge my car. Same with the Bosch scanner at Oriellys. Will try to scan it again tomorrow with a different scanner and see what happens.

Do either of those places have the ALDL cable? It can be as simple as a wrong cable or the scan tool doesn't have the ability to go back to OBD1 without being programmed for it. I imagine this would be moreso true for the oriellys Bosch scanner. Most stores have a machine that will only go back to 96 for simplicity since they all use the same connector.

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Do either of those places have the ALDL cable? It can be as simple as a wrong cable or the scan tool doesn't have the ability to go back to OBD1 without being programmed for it. I imagine this would be moreso true for the oriellys Bosch scanner. Most stores have a machine that will only go back to 96 for simplicity since they all use the same connector.

They both have the OBD1 connector adapter.

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IF (big IF) the scan tool has appropriate software to deal with the model and year you're working with, maybe you have a defect in the vehicle wiring.

 

Does the MIL come on when the key is turned to "Ignition" but before you crank the starter?

 

Have you verified the ECM fuse(s)?

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IF (big IF) the scan tool has appropriate software to deal with the model and year you're working with, maybe you have a defect in the vehicle wiring.

 

Does the MIL come on when the key is turned to "Ignition" but before you crank the starter?

 

Have you verified the ECM fuse(s)?

The Bosch Scanner at Oriellys had the make and model, but not appropriate software to recognize it. Couldn't get any codes from that one.

 

Borrowed an older Matco Tools Determinator Scanner and got the Codes in less than a minute. Simple O2 and EGR codes were all that was present at the time I checked. Going to keep an eye on it and see if any more codes pop up.

 

And of course, resolve these codes.

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