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Old 07-29-2011, 11:05 PM   #1
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Default 95 trans am, No start, new opti, ICM, coil

This is my first post, but I want to say hi to all the members out there..

I am having a terrible time with my 1995 Trans am. Here is the story:

I recently bought this car in May with a bad waterpump which I replaced. It ran great for about two months until it just died on me when I went to pass someone on the road and everything just cut out.. no power, power steering, or power brakes..

We got it back home and figured it was the ICM.

We replaced that to no avail, then ordered and replaced the opti (figured since it got rained on by the waterpump), then the coil.

After all of this, still no change..

Symptoms are: Cranks but wont turn over, we have fuel pressure, no spark at ign coil, no injector pulse.

I'm very frustrated at this point and any ideas would be incredible.. Thanks in advance.
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Old 07-30-2011, 06:15 AM   #2
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Any chance your security light is staying on? When you turn key on security light should come on then turn off after a few seconds. This is the vats system. If it is not in order it was designed by the factory to disable the fuel injectors and keep the starter from turning over. Being your car is 16 years old and has probably had many owners, someone along the way could have bypassed the starter relay, so with a vats problem the starter works but the fuel injectors don't. Also have you scanned for codes. There are codes that don't turn the ses light on, but when present disable your car. Dtc 16 opti low resolution is 1 of these. When active it not only shuts the fuel injectors down, but also disables the ignition system. So you need to scan for codes. Your 95 has an obd1 computer system with an obd2 16 pin aldl, so you need a scanner that does both obd1 and obd2. They are usually $200 or more. Or you can buy a special cable that runs between the car's aldl and your home computer or laptop and download a program called freescan to scan for codes and check data once its running. Do a search with freescan. You can also download the tria version of datamaster. It comes with 20 free datalogs. Get it at www.tunercat.com Cable available at www.akmcables.com

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Old 07-30-2011, 06:34 AM   #3
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After you scan for codes, and I think you may have 1 or more with no spark or injector action, you can go to www.shbox.com and check what the codes mean. He also has much other good lt1 info including a write up on the security system. Did you use a fuel pressure tester to test fuel pressure? If not get one, you should have 43 psi when you turn key on and it primes. Seeing its new to you, did you change the fuel filter? Also what brand of opti did you buy. The manufactured opti's and cheap Chinese made new ones have a high failure rate and you could have gotten a bad one out of the box. Shoebox's site also has opti and coil testing procedures. In fact I suggest you learning everything you can from the site. Also your 95 opti has the type 2 opti on it. Did you install it correctly. It is made so mis installation is much easier then the earlier type 1 opti. Again shoebox has a pic of back of opti and the proper install place where the cam dowel goes.
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Old 07-30-2011, 08:59 AM   #4
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Quote:
Originally Posted by cocobolo95 View Post
Any chance your security light is staying on?
He said it cranks. VATS would not allow that, so it's not the problem.

OP, check your fuses first. Specifically, the PCM ignition fuse.
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Old 07-30-2011, 09:05 AM   #5
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Spartan, these cars are old and have had many owners as a rule. Somewhere along the way a previous owener could have bypassed the starter so when vats acts up the engine still cranks. Very easy to do, just put the purple and the yellow wire together on the anti theft relay. My car if the security light comes on still cranks because someone before me bypassed the anti theft relay. Please think about your answers before adding conflicting info. Yes theres a good chance that the atr has not been bypassed and the car won't crank, but just as good of a chance that it has been bypassed. Wish the lottery had that kind of odds.
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Old 07-30-2011, 03:55 PM   #6
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Thanks for all the info guys, but let me give a little more info based on your comments.. I have scanned this by using this technique: http://shbox.com/1/xraycable.jpg

There were no codes but I could read all types of info about the car including the VATS status which is enabled. I unplugged the security cable under the dash and this stops all cranking.

The opti is a delphi model brand new.

I have also checked all the fuses.

Right now I will be putting in a new opti harness because my clip on the old one is broken but when I unplug the old one and plug it back it the fans kick in so I don't think there is a problem with it.

Also the fuel pressure is good a little over 40psi

I have done almost all of the tests for the opti and it's checking out except the AC voltage test. For some reason both end pins on the icm harness are live.. i.e. no ground..

Lastly, would a faulty pcm cause this? I have replaced everything else and I am wondering if there is a test I could do or if it should be throwing codes?

Thank you guys so much again, it is greatly appreciated
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Old 07-30-2011, 04:01 PM   #7
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I believe I installed the opti correctly. It took a lot of time to find the correct pin location but once we got it on it screwed in smoothly. I did not change out the fuel filter but I am getting adequate fuel about 43 psi.
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Old 07-30-2011, 04:05 PM   #8
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Pcm's on these cars have a low failure rate, but that doesn't mean they can't fail. I always keep a spare pcm just for those occasions when your ready to tear your hair out because nothing else fixed the problem. here's a handy search engine for checking salvage yards. www.car-part.com Or find one on craigslist. The part you put in about both pins of the harness being live doesn't sound right to me.

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Old 07-30-2011, 04:11 PM   #9
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I have a 95 GM factory manual, if it would help, tommorrow I could scan some revelvent troubleshooting pages from it and send them to you. If you want the pages pm me with your e-mail address.
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Old 07-30-2011, 04:21 PM   #10
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Dude, please can you tell me if the security flashes in the gauges, if this happens probably you have a VAPS problems. That's happens to me today, I was getting crazy because without any reason I lose everything like you say, no spark, no current on the injectors, all that, maybe I can help you, I made troubleshooting today and Now Im ****ing happy
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Old 07-30-2011, 05:05 PM   #11
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Unfortunately my car is at a friends house so I wont be able to check the security light until maybe tomorrow. But what do you do to fix it? And is the same as VATS?

But I do have access to a 93 pcm from a friend. Will this work just to troubleshoot or will I need one from a 95? They are both LT1s.
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Old 07-30-2011, 05:15 PM   #12
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Default Vaps/bcm

well, this is what I learn today. With out reason my car doesn't start in the morning, the I saw the security light flashing in the gauges. I didn't understand why, then I measure the resistance pellet from my Key and it was around 12 K ohms, later i tried measured this value in the connector, bingo no value there, so I duplicate the resistance value and my car starts.

OK The VAPS belong the firebirds from 1993 to 1995, so please if your car is an 95 use the original. BCM is the same thing but for the 96 and 97 ( i got an 96).
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Old 07-30-2011, 06:28 PM   #13
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Okay so we found that wire last night and unhooked it to see what would happen. It didn't crank.. hooked it back up, and I could prolly crank it all night without starting. So would it be safe to assume my key is giving the correct resistance because if not, I dont think it would crank. Sorry, but I'm just trying to understand how this security system works
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Old 07-30-2011, 06:40 PM   #14
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If you go back to post # 3 the link I provided to shoebox's site has a good write up on the security system Since you have a 95, if you send me your pcm I can tune vats out so you don't have to worry about it. $20 to retune + $20 for shipping provided your in the continental US.

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Old 07-31-2011, 07:53 AM   #15
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And you need a 94 or 95 pcm to use on your car. The 93 ecm is completely different and won't even hook up. You need to find a pcm from another f-body with the same transmission. There are other considerations like rear end ratio, tire size but as they only affect rolling down the road the f-body and trans are the important things. You can change the other things later with a simple re flash of the pcm. If you want the particulars on re flashing the pcm, let me know.
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