# 94 Olds check engine light diagnosis



## mrqikfix (Dec 26, 2014)

How do I find the offending system causing the "service engine soon" light to illuminate on a 94 Olds Cutlass Ciera? The vehicle seems to function normally, but something is obviously not in proper order. Since it is pre-96, the ODB 1 & 2 scanners are of no use, and the dealership charges $100/hour for diagnostic testing. I am familiar with other older GM products that allow a flashing code to be displayed via the check engine light, by grounding one of the underdash diagnostic connector terminals and then turning the ignition switch to the on position. This vehicle has a 12 pin connector with only three wires installed in it. Does anyone know if the code(s) can be determined in this manner (and if so, which wire gets grounded) or if other specialized equipment is required, instead? Any assistance available would be greatly appreciated!


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## Midnight Tech (Dec 31, 2001)

Can you post a picture of that car's ALDL please?


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## bruiser (Jul 30, 2005)

I think '93 was the last year the paper clip trick would work on a GM vehicle. You need to find someone that is able to scan/pull codes from an OBD1 car.


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## mrqikfix (Dec 26, 2014)

Here is the ALDL, with the following wiring attached: terminal A has black w/ white trace, K has violet, and M has orange.


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## Wrench97 (May 10, 2008)

You can't blink them out you need a scan tool.
The old method was to connect terminals A&B, there is no wire in B on your connector.


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## mrqikfix (Dec 26, 2014)

Understood. The next question, is which scanner?  I was of the belief that the OBD (both I & II series) devices are not usable on pre-1996 vehicles. If that is true (or at least, applicable in this case) how about the Autel MaxiDAS unit, which is sold at Harbor Freight? The user manual for that product mentions compatibility with nearly all vehicle formats, not just the OBD series. However, even on sale and with a coupon, the MaxiDAS will set you back almost $900, which is a pretty stiff price for the DIY mechanic to afford.


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## Wrench97 (May 10, 2008)

You would be better off finding a shop that has one to read the codes for you most independent shops will do it for a minimal charge.


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## bruiser (Jul 30, 2005)

There are scan tools to do only OBD1, but they are scarce as hen's teeth. There are scan tools that do only OBD2, and they are everywhere. And, there are scan tools that will do both. I have one that will do both. It's no longer made. Check out Auto X-Ray as they have one that will do both, and it's a lot cheaper than the MaxiDas. I'd look on Amazon for scan tools.


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## wolfen1086 (Oct 4, 2007)

My suggestion is go to a parts store in your area and see if they will scan it for free, I don't know an=bout where you are, but here in Va Bach everywhere scans cars
even the guy at 711 on the corner where I live has a scan tool in his car


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## bruiser (Jul 30, 2005)

Most parts stores only scan OBDII these days.


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## wolfen1086 (Oct 4, 2007)

The ones here in Va Beach scan both, unless I go on with a check engine light on MY Jeep, then the hand me a scanner and the manager says " do it your damn self your here enough and do it for customers I think you work here half the time "


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## Basementgeek (Feb 7, 2005)

Find a smaller shop, they generally work on older vehicles and probably have the scanner, however they will probably charge you you.

BG


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## mrqikfix (Dec 26, 2014)

I hear you...what do you know about the TOAD software (Total OBD & ECU Auto Diagnostics) from Total Car Diagnostics? It is a CD for use with a laptop, that addresses both trouble codes and performance tuning (where applicable), on nearly all vehicles (foreign & domestic, both OBD platforms plus others, etc.). My vehicle appears to be listed for compatibility, but I am currently awaiting confirmation from the vendor, before purchasing it from eBay ($52 incl shipping). The cost seems very reasonable for all that it promises to offer, including future updates for new systems/protocols. Has anyone used this software, or had any experience with it, especially pertaining to an older (OBD-1) vehicle?


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## mrqikfix (Dec 26, 2014)

Here's an update on this issue, in case anyone wonders how it turned out. I was able to find a small auto repair shop that offered a free "check engine light" diagnosis, and I believe I saw a Snap-On scanner being utilized to do this. The result was determined to be a faulty EGR valve, which made sense due to the rough and erratic idle of the vehicle. I replaced the valve with a new one myself, which corrected the uneven idle problem. However, the MIL is still illuminated due to not clearing the existing trouble code(s). Not wanting to spend the $32 at the same repair shop to have the code cleared, I thought it would be a better investment to put that amount toward the purchase of a suitable scanner for future use on this vehicle, as well as others that were of both OBD1 & OBD2 vintage. Looking online, I discovered that the Actron CP9185 is capable of use with both OBD1 & 2, if specific additional cables are purchased for the OBD1 application desired. The CP9190 is also available, which includes the CP9185 scanner plus all the optional cables for use on the various OBD1 systems. There are a lot of these Actron units for sale online, both new and used. However, I started reading the reviews, and now I'm unsure about the value of obtaining one for my present and future vehicle scanning needs. Some people say they work great, and others say they are junk with all kinds of problems. It seems like the first category is composed of "casual" users who don't go into much depth with the devices, and the second group is composed of persons who are more "techies"/semi-professional mechanics who have a good knowledge of both vehicle systems and computers. These folks readily state the shortcomings of the Actron units, and the problems they have experienced (typically, software update difficulties/unavailability) in trying to resolve those shortcomings. Has anyone in TSFland had experience with the Actron CP9185/9190, such that I might learn if one of these units is worth my money to purchase or not???


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## bruiser (Jul 30, 2005)

To turn the SES off, disconnect the battery for about a minute. The PCM will relearn everything after you drive a few miles. If any new codes are stored, the SES will come back on. 

An independent shop is likely to have their old OBD1 scanners and readers still around. It's getting harder and harder to find OBD1 stuff. I have a scan tool that does both, and has all the cables. I bought it some years ago, from the original Auto X-ray company. That company was sold, and the reviews say the ones being made today aren't as good.


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## Wrench97 (May 10, 2008)

I use a Actron unit to quickly view or delete codes, it's faster then setting up the snapon modis unit to clear codes after a repair, however when troubleshooting is needed the resources available on the modis are far superior.
At roughly $100 vs over $3000 for the modis for your needs the Actron is the choice.


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## mrqikfix (Dec 26, 2014)

Well guys, here is "the rest of the story", as Paul Harvey used to say...I bought an Actron CP9190 and found that there were current and historic fault codes for each of the three sections of the electronic EGR valve, which was just replaced a few months ago. I checked out some online blogs and videos on this relative to the GM 3.1L V6 engines, and they all advised that the most common cause of the EGR codes was due to a blocked passage in the intake manifold, running from the base of the EGR valve to just past the throttle body. I took it apart and BINGO! It was completely blocked with carbon residue. One of the sites suggested using a piece of wire coat hanger in a drill to break it up, which really is the way to go. The curved passage cannot be cleared with anything that is straight and rigid, so a stiff wire that is able to bend and still exert significant rotary force is definitely the technique to employ. Carb cleaner spray is also a good choice to saturate the blockage, as well as to perform the final cleanup after boring out the passage. 

If I would have checked online before initially replacing the EGR valve, I could have saved myself the trouble of taking it off a second time to clean the passage, which of course required a new gasket for the valve. The thing that had me initially baffled was the fact that the engine was idling poorly before the original EGR valve was replaced, indicating that exhaust gasses were making their way into the intake, although the old valve was allowing them to leak past when the computer was not calling for it to be open. I figured that the passage had to be open for this to occur, so how could it now be blocked? However, I remembered only cleaning out a small amount of carbon buildup directly below the valve when I replaced it, or at least I thought I cleaned it out! More likely, I dislodged just enough of it to allow the engine to draw it into the small remaining space in the passage, until it was completely blocked shut! That explained the contrast between the old and new valves' opposing symptoms.

So, the bottom line is, don't think you are too smart to learn something from other people, particularly on a task you have never performed before. Also, don't allow 'logic" to override good judgement, and never skip past a typical cause for a problem without actually investigating it as the potential solution.

I hope I will be able to utilize my expensive new scanner on many more vehicle trouble codes in the days and months ahead, so that it pays for itself on money saved by continuing to avoid costly repair shops. I'm sure there will be lots of opportunities to use it, just as soon as I tell all my friends that I have it...oh, and by the way, you can consider this matter CLOSED! Thanks to all who provided information and suggestions. I trust others will read this and save themselves some time and frustration on a similar problem!


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## Wrench97 (May 10, 2008)

Thanks for the update.


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## SABL (Jul 4, 2008)

Wrench97 said:


> Thanks for the update.


Ditto.....thanks.

With any real luck you won't need the scanner......and have trouble-free driving............................................................................Good day!!


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