Code 27?
#16
Re: Code 27?
If you have a multimeter, there is a test on Shoebox's site for diagnosing a bad opti that covers the ICM. I would follow this to make sure you don't have any problems there.
4th Gen LT1 F-body Tech Articles
Also check the coil to make sure it isn't dead. Here is how you check it.
http://shbox.com/1/coil_testing.jpg
4th Gen LT1 F-body Tech Articles
Also check the coil to make sure it isn't dead. Here is how you check it.
http://shbox.com/1/coil_testing.jpg
#21
Re: Code 27?
Pull a plug wire off, and hold it near a ground (not with your hand, or a metal tool) while someone cranks the engine, and look for a spark. If no spark at the plugs, pull the end of the coil wire out of the Opti and do the same test.
#22
Re: Code 27?
Ok. I'll try tom when I have help. Could it be possible something with my key? Or the ignition? I just noticed the ignition turns without key in it. Security light does not come
On when trying to start. Just the service engine soon and check gauges lights
On when trying to start. Just the service engine soon and check gauges lights
#23
Re: Code 27?
Can you hear the fuel pump run for a few seconds when you turn the key to on (not start but just on)? If Vats was killing spark, my understanding is it kills fuel too.
Edit: I kinda worded that badly. VATS enables spark and fuel. If VATS enables fuel (IE you hear the fuel pump prime), you should get spark. Unless something is wrong of course.
Edit: I kinda worded that badly. VATS enables spark and fuel. If VATS enables fuel (IE you hear the fuel pump prime), you should get spark. Unless something is wrong of course.
Last edited by DelSoto; 07-02-2015 at 09:38 PM.
#24
Re: Code 27?
I just perused Shoebox's site and I may have misunderstood the fuel shutoff with vats. I think the pump still primes so that's a lousy test. Fred will surely know... when he sees this, he will be able to tell you.
#25
Re: Code 27?
Courtesy of Shoebox. 4th Gen LT1 F-Body Tech-PassKey/VATS
Normal Operation
When you insert the key and turn to ON[RUN], the SECURITY lamp will light during the bulb check. The TDM reads the resistance of the key pellet and compares that to what is stored in its memory. If the reading matches, the SECURITY lamp should go out after 4 or 5 seconds.
The TDM (or BCM) sends a ground to the TDR to allow the starter to crank when you turn to the START position. Simultaneously, it sends a signal to the computer to allow fuel to the injectors. Your engine is allowed to start.
Since your light doesn't come on at all?? Broken bulb?
Normal Operation
When you insert the key and turn to ON[RUN], the SECURITY lamp will light during the bulb check. The TDM reads the resistance of the key pellet and compares that to what is stored in its memory. If the reading matches, the SECURITY lamp should go out after 4 or 5 seconds.
The TDM (or BCM) sends a ground to the TDR to allow the starter to crank when you turn to the START position. Simultaneously, it sends a signal to the computer to allow fuel to the injectors. Your engine is allowed to start.
Since your light doesn't come on at all?? Broken bulb?
#26
Re: Code 27?
Hmm. Interesting. I will closely look tom at the bulbs one more time. I'm going to check that spark from the opti wire too. I'm just trying to narrow down. Yes I hear the fuel pump prime for a little.
#28
Re: Code 27?
I just went back and reread this thread. You mentioned the original work done. Water pump and plugs. It is entirely possible, yes. The opti does not like coolant and if coolant was spilled on it during the water pump change....well....there ya go.
#29
Re: Code 27?
Ok. That's what I was thinking but before died in my driveway the car ran so perfect t for 2 days. Never any signs. Than just would start only cranked. I thought opti have symptoms.
He is an old school gm mechanic and swears by some aftermarket opti. Told him I wanted GM but says he will warranty for a long time if I go aftermarket.
He is an old school gm mechanic and swears by some aftermarket opti. Told him I wanted GM but says he will warranty for a long time if I go aftermarket.
#30
Re: Code 27?
DTC 36 sets when the PCM can't find the high resolution pulse signal from the cam position sensor, but the engine should still run. It can time the injectors and spark off the low res pulse.
Did you ever check to see if you have spark at the coil wire?