Trouble codes for GM

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  #1  
Old 02-19-04, 06:40 PM
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Trouble codes for GM

I have a 1992 88 Oldsmobile 3.8 liter that has been getting less mpg/ than it used to. I'm setting several codes in the computer. It has been setting a code 13 ( oxygen sensor open ) for quite a while, and recently set a code 26 ( Quad driver ) and a code 44 ( lean exhaust) . I've replaced the oxygen sensor, I replaced the catalytic converter ( it was rattling and was starting to break up). I've replaced the plugs, wires, air & fuel filter, Went thru and replced old and weak vacum lines, and cleaned the throttle body. Most of the time it seems to run pretty good as far as drivability goes. It does get a bug up its exhaust occaisonally though. Any help would be appreciated.
 
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Old 02-20-04, 04:17 AM
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That one's not going to be easy because of that quad driver code. You may have a component overloading the quad driver or you may have a bad computer. Not a job for a DIY.
 
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Old 02-20-04, 11:23 AM
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If you can get a OEM manual for your car, checking the quads are explained in it. The manual will also tell you which sensors apply to which quad. It can be confusing. Testing requires a DVOM with fused amp meter. As I recall 10 Amps is plenty.
You don't let anyone replace your computer until they check the components which are monitored by the quad or you could wind up with a new fried computer.
 
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Old 02-20-04, 04:06 PM
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Originally posted by dirty dan
It can be confusing. Testing requires a DVOM with fused amp meter. As I recall 10 Amps is plenty.
You don't let anyone replace your computer until they check the components which are monitored by the quad or you could wind up with a new fried computer.
10 amps! what are you kidding. A quad driver can operate up to 4 acuators with a total amperage not to exceed 300ma That's .3 of one amp before it fries the quad driver. The computer can have 2 or 3 quad drivers. The way it is tested is to check resistance in the component and use Ohm's law to calculate the amperage draw. confused yet? That's why I said it may not be a DIY type job and there is always the risk of damaging the computer.
 
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Old 02-23-04, 05:08 AM
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Like I said, a meter that will carry 10 amps is plenty. My GM manual says that the quad's sensors if failed could pull up to 2.5 amps due to faulty circuit/sensor. You test with an amp meter that can't handle at least 2.5 amps and you're going to fry your tool. You wouldn't want to ruin your amp meter along with the already failed ECM.
 
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Old 02-23-04, 06:02 AM
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you don't test sensors with a ammeter...

...use the ammeter to power up any and all ECM controlled outputs (a/c relay, TCC solenoid, injectors, F/P relay, and so on) until you find the one that's drawing too much...the draw is different on different outputs...Ohm's law is a big help here
 
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Old 02-23-04, 04:35 PM
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An ammeter can be used on most actuators IF the ECM is taken out of the circuit first and it is read from then feed side. The max amperage tolerable is .75 amps. My understanding is that can't be done on a TCC though. Reading resistance and converting to current with ohm's law with work on all actuators except if your looking for a failure that occurs after the component overheats, you won't find it that way.
 
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Old 02-23-04, 06:15 PM
mike from nj
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you might be over-analyzing this one.

whenever i have an isuzu(GM electronics), and occasionly they come in with a pretty good intake manifold leak, i get two codes for lean exhaust(right and left) and 50% of the time i'll have a 'quad driver' error code too. i've never even tried to diagnose it, i fix the intake leak, clear the codes, and have never had 1 of those 'quad driver' codes come back yet. being under warranty, i'm confident they would be right back. also, they come back for simple maintenance, still with no light on. this is about 45-50 cars so far.

i learned in this thread, what that means now, but i would fix the other code first(lean exhaust), erase them all, and see if it comes back, before getting too involved.
 
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Old 02-23-04, 07:00 PM
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That's probably good advice but what on earth is setting the quad code?
 
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Old 02-24-04, 06:44 AM
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desi...

good point about removing the ECM from the circuit...ALWAYS!!!

and mike...i'm curious too...why the quad code for a simple air leak? don't get me wrong...when confronted with conflicting data and results...I always take results!! thanks for sharing that info...could come in very handy at some point.
 
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Old 02-24-04, 08:43 PM
mike from nj
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it's more than a simple air leak, it's whistling and barely idling. sometimes it even has a few misfire codes too. if the code ever returns, i'll take the time to figure it out. (now that i know what is happening)
 
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Old 02-26-04, 05:08 PM
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lost my post

I ve been looking for my post but could only find it with a search. Can anyone tell me what happened to it. p.s. thanks for all the suggestions so far
 
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Old 02-27-04, 02:54 AM
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It's been right here seeing activity. Might have been on second page.
 
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Old 02-27-04, 02:15 PM
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still working on it

well I had cleared all the codes and one by one they all come back. Code 13 first, Just cant keep that persstant little devil away more than a day. 26 and 44 came back during the week some time. But this time they brought a friend (they must think my car is some kind of half way house for lost or abused codes or something. ) code 62 (cruise vac. solenoid circuit). I have been having trouble with my cruise control dropping out. I wouldn't mind putting it in the shop to run a diagnostic if I was sure they would find the problem. I think it almost has to be a vacum problem but I just checked all the hoses last night and everything was connected. and the hoses are relatively new. Last summer I was checking the vacum lines and had a connecter that was cracked that ran two lines to the fuel pressure regulator and I think it was the controls in the interior. It was a real weird connector that dropped the line size down to the regulator, so I had to rig up a connector to fit it. I couldn't find one at the auto parts store and they didn't have one at the dealer either, I went to the dealer first and found something at the napa store that work ( or maybe it didn't) Any fresh ideas with this new information would be greatly appreciated. Also I hooked up a vacum guage and it was holding a steady 22 inches of vacum.
 

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Old 03-02-04, 06:53 PM
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update on problem

I got to thinking about my problem and remembered that last year my air conditoining compressor froze up and stalled the engine. I had to disconnect it and buy a smaller belt. Today I got to thinking the way all the sensors are interconnected to the computer( like high and low pressure readings ) if that could be sending the computer mixed messages. All I did was bypass the compressor with a shorter belt. I never disconnected the wiring connector to it. Just a thought to get your wheels turning. All responses are appreciated.
 
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