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COOLING FAN starts when reading codes


kurtk
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Hello! First post. I just used paper clip to read codes on 1990 Park Ave and fan came on. Code only 12 12 12 over and over. i just bought the big Shop manuals to try to fix stalling issue. Starts and runs really great until warm. Then it might stall at idle sometimes. It never restarts when at full temp (cranks OK). Always starts right up when cooled down.

HELP Should the fan kick on when reading codes?

Why am I not getting any codes?

Edited by kurtk (see edit history)
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IIRC, code 12 just indicates diagnostic mode. It will repeat 3 times followed by any stored codes and ends with 12 again. Not sure if the fan should kick on in this mode. Possible.

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Welcome to the AACA Discussion Forum.

I am relatively sure that the fan does come on when you are reading codes on that. I seem to remember my 1989 Park Avenue exhibiting the same symptom.

I would guess that a fuel filter needing to be replaced or perhaps a failing fuel pump or failing ignition module might be a few of the "usual suspects".

Also, if you scroll down to the Buick Section of the forum you will find a lot of Buick Experts who reguarly answer questions on similar issues.

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Matthew,

So you have one too! NICE CAR!

I just got this one and it's been a family handmedown. New ICM, Fuelfilter, Vac hoses. No codes if I'm doing it right.

I will look for more postings. The one I found... the guy did not finish the thread with what finally fixed it.......:(

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If you have already replaced the fuel filter and Ignition Control Module, A set of coil packs might be another possibility. Other than that, I would suspect some loose and/or corroded wiring somewhere causing an intermittant problem.

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I thread I was reading with near identical symptoms ended with COIL PACK UPGRADE for the fix. Can't seam to find the upgrade used.

Right now, I just wanted to read any codes properly. Can i run car with the paper clip in there. Will it tell me anything while running?

The codes when not running were just a repeating 12 12 12 12 12 12 on and on...

Based on other research MAF sensor (will clean next) or Crack sensor (will pay to have that done).

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If you are simply getting "12" repeated by flashing as your codes, you do not have any trouble codes. No, you can't run the car with the paper clip reading codes. From memory there are two different brands of coil packs. Some people swear by one and swear about the other. I would simply go to your favorite auto parts supply house and get whatever brand coils they have in stock for your car. Even if that does not fix it, it would not hurt to have a spare set of coils available if you ever take the car on long road trips. The Crank Position Sensor is not really that hard to replace if you follow the instructions that can be found on this forum. I can help you find that thread if you need to read it.

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Thanks,

You answered my question. Send me link to other troubleshooting or fixes for stall issues. Such a nice car and runs so good too.

Last stall / No-start was in a carwash.

Never again

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Those cars were good looking, but boy, what a nightmare for most customers at that time! I was then recently appointed Service District manager in Switzerland when those cars were on the road. I remember GM issued a booklet to help the dealers to find the problem(s). Unfortunately for you, I don't have it anymore, I'm retired since 2002.

I remember also that many ECMs were replaced in warranty. When hot, coils could let to the probelm you have. I believe there is an idle learning procedure when the battery was disconnected; this is explained in the shop manual.

Good luck!

Edit: there were a useful test to know if the ECM or the mass air flow sensor had cold solders: a light tap on those 2 elements while the engine was running. If there was a bad solder joint, the engine would stall.

Edited by Roger Zimmermann
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Hello! First post. I just used paper clip to read codes on 1990 Park Ave and fan came on. Code only 12 12 12 over and over. i just bought the big Shop manuals to try to fix stalling issue. Starts and runs really great until warm. Then it might stall at idle sometimes. It never restarts when at full temp (cranks OK). Always starts right up when cooled down.

HELP Should the fan kick on when reading codes?

Why am I not getting any codes?

Now you need to read that factory service manual. Yes, the cooling fan comes on when you put the car in diagnostic mode by jumpering the ALDL connector. And you don't have any error codes because there are a lot of failures that won't set a code. The OBD I system has very limited capability (it's mid-1980s technology) and only monitors a handful of items. The manual has detailed diagnostic procedures. Follow them.

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That was my next check. All vac lines were old and crumbly so they are mostly fixed now... Need to read up on that IAC valve first. Seems I read that if gas gets into vac line change oil and replace that part. THKs

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I have bought the BIG shop manual. Are any of these scan tools OBD1 or software programs any help at all on these old systems? Ebay for $10.00 - $300.00. My Dad, Mom, Brother and then Niece spent $500 on diagnostic charges (over the years) and this intermitant stalling never went away completely.

I think I did right and determined there are not any error codes right now.

Would you get one of these scan tools?

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When hot, coils could let to the probelm you have. I believe there is an idle learning procedure when the battery was disconnected; this is explained in the shop manual.

Good luck!

Edit: there were a useful test to know if the ECM or the mass air flow sensor had cold solders: a light tap on those 2 elements while the engine was running. If there was a bad solder joint, the engine would stall.

OK, It did have new battery recently. Hot coils might be it! THANKS

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Most probably you would see nothing. As Joe Pavadano wrote, OBD1 is rather crude. The GM scan tool (TECH 1) could trigger a freeze frame when an intermitent problem is present, but I doubt that the scan tool would be a help here. Maybe others may have a different opinion, of course.

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Most probably you would see nothing. As Joe Pavadano wrote, OBD1 is rather crude. The GM scan tool (TECH 1) could trigger a freeze frame when an intermitent problem is present, but I doubt that the scan tool would be a help here. Maybe others may have a different opinion, of course.

I agree with Roger. I have an OTC Genysis scan tool and the data available from an OBD I system is minimal. The one thing a scan tool will do is give you access to the raw sensor readings (like O2 sensor volts or temp sensor reading). This can help when the problem is a screwy sensor that isn't quite far enough off to set a code.

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The code 12 if my memory is correct is the code for no tachometer signal from the engine to the ECM. This is the test code that you would get when the ignition is on and the engine is not running.

Roger is right that there was a light blue booklet put out to fix the intermittent stalling problems on the 3800 v-6 vehicles. The repairs were easy, but the new electronics on the vehicles had a lot of persons overlooking the obvious.

The two types of coils were made by Magnavox and Delco. The Magnavox was a one piece coil and the Delco were three individual coils.

The four big items that could cause the car to stall were a bad mass air flow sensor, crankshaft sensor, bad coil, and finally a bad ground located under the coil pack.

To check the mass air flow sensor, GENTLY tap on the sensor. If the car stalls, replace the sensor. Same goes for the crank shaft sensor. A light tap on the sensor holder could cause the car to stall. Some of this could be caused by dirt/rocks/debris for the c/shaft sensor. If you replace the crankshaft sensor be sure the sensor is not hitting the vanes on the crankshaft pulley.

For the ground, put a wrench on the ground and make sure it is tight.

For a coil check. get a HEI spark tester like an AC-125 similar to this one..

http://s31.photobucket.com/user/tyad/media/ST125SparkTester-1.jpg.html

Unplug one of the spark plug leads that goes to the coil, put the wire on the plug top and clip the tester to the coil top.

Run the car for maybe 5 minutes and if the car starts to falter or stall, change the coil.

Do this for each coil and replace any of the coils that falter.

Hope this helps.

PS. a scanner will not detect or fix this problem.

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