dually681

iTrader: (4)

Guys, i need some help. i got a 95 trans am lt1 mt6
no spark. i see no ses light.
i did the test for opti, the instructions seem wrong though.
it says to unplug the opti harness from the ecm. i did so and on the ecm side i have 12v and ground no +5 on either the purple w or the red blk wires.
when i connect it back and check the voltage inline then i get +5 on one of the wires but not on both. depends if i crank over the car or not.
this is of course with KOEO.
im at wits ends, can anyone give me something else to check....
I also changed the ecm with another unit and still no go.
no spark at the plugs or at te coil. no pulse at the injectors with noid light on any of them.

Edit: checked shbox opti diagnostic and still no go.
could it be wiring before the pcm missing power or a ground?

please help...

ps this car has been parked for about 1.5 yrs. just cleaned out the fuel and flushed the tank also.
changed the head gaskets and now this.

dually681

iTrader: (4)

Well I still need help from the LT1 Guru's !
I went out and bought a reman optispark.
put it on and no spark.
so i said screw it and took it off and went back to parts store.
Got a new one and still same no spark.
checked coil and ICM both good at parts store so not a problem there...

Any bright ideas???

littless

I just went Through the same problem. The new harness that came with the OPTi spark was pluged in backwards And didn't realize it. Didn't think that could happen. Good luck

dually681

iTrader: (4)

cool. something new i hadnt checked yet.
so i went outside and checked to make sure the harness wasnt backwards and no luck.
it was on right.
so i checked something else thats in the back of my mind.
the data link i cant connect my scanner software tunercat nothing.
so i checked the fuse to the cigar/horn and the radio one and both good. w DVM.
next i gotta check the tan cable D30 serial data cable to the pcm.

if u guys think of anything else please let me know...

thanks.....

AdsoYo

iTrader: (1)

So the starter still works and it just cranks?

I had an issue with a brand new opti harness being wired backwards so I found a diagram from shoebox's site. I changed the diagram on the opti plug so it matches my car's configuration (the diagram was backwards for me but shoebox said no one has ever said anything to him about it, so I don't know).



Have you verified the ICM and coil harnesses are functioning properly?

shbox

You realize that your corrected diagram says the same thing as the original. A goes to A, B to B... just like the original. Yours is functionally the same. Wiring diagrams are often drawn so lines don't cross, so they are easier to follow.
The connector plug may be labled ABCD, but you flip it over and it is DCBA. Not saying a factory manual can't have an error (because they often do), but you'd think they would correct it during the many years they were produced.

dually681

iTrader: (4)

actually my factory service manual has them labeled like on shboxs site..however i do see what you mean by backwards.. hehe

well i think i may have found my problem.
we got very low fuel pressure....like a very soft flow. not even 1 psi.
any suggestions what page to start at in the service manual?

shbox

Try the prime connector and see if the pump is working at all. If not, you might want to check to see if power is getting to it.

http://shbox.com/1/fuel_pump_wiring.jpg

http://shbox.com/1/fuel_pump_connector.jpg

dually681

iTrader: (4)

thnaks shbox made some serious progress here.
took the relay and jumped it, boom pump ran so im sure the wiring to the back is good.
pump made great pressure.
next traced the green wire to pcm no power at the connector from pcm.
starting to think my pcm is bad.
no low res, now high res, no fuel pump.

welll im heading to auto parts to return my new opti and to see if they have reman pcm's.

saw some cardone ecm/pcm units on advance's website....

Thank you guys will keep you posted.

AdsoYo

iTrader: (1)

didn't you already try a different pcm?

dually681

iTrader: (4)

yes i did, however it was a junkyard pcm.
swapped it just a while ago and same symptoms exist.
checked power to pcm and grounds all checked ok.

AdsoYo

iTrader: (1)

Were you able to get the data link connector figured out? I know you said there's no SES light but knowing what codes are present could be a big help.

So there's no spark, no fuel pressure, data link connector under the dash doesn't work but the PCM is getting the correct juice. Does that summarize accurately?

dually681

iTrader: (4)

man you got the summary down packed.
the datalink is not getting signal.
i got +12 and ground and checked the tan signal wire to pcm and wire is checking ok, not open.
so this all boils down to a bad pcm!!!///????

dually681

iTrader: (4)

ok got a ocm from a known fbody shop and tried it. nothing. that wasnt it. still have no pcm signal to fuel pump, pump works great wheni jumper the relay in kick panel. traced wire to pcm and no voltage coming from that wire.
no low res +5 , yes high res +5.

can anyone chime in and tell me what could be causing the pcm to not send the proper fuel on signal and no low res voltage to the opti???

dually681

iTrader: (4)

Here is a stupid question !!!

If I turn the key on and SECURITY comes on then goes off is the VATS killing the pcm?
thus no fuel pump and no opti???

shbox

No, you see the security light as it goes through its test and goes out. That means all is normal and working.

dually681

iTrader: (4)

ok folks heres the low down
Problem resolved we have start !!!
it was under hood fuse panel missing 3 fuses.
3,4 hdlp dr hdlp L and R, also the one not labelled 8.
will upload a pic tonite.
i cant believe something so simple caused me such a headache... =)
maybe this will help someone in the future.

dually681

iTrader: (4)

I almost forgot....

THANKS !!!
thanks to all that have given their input and helped me throughout the troubleshooting process.
its all been worth it.
By the way my MSD opti is sparking super hot.... love it !

shbox

U/H fuse 8 on a 95 is only the power to the PCM. I guess it is important after all.