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1996 Psyco electrical problem/ Need experts here!

vigman

Motor head!!!!
Joined
Feb 13, 2001
Messages
3,471
Location
Valencia, CA,USA
Corvette
88 Convert ( SOLD ) /1973 coupe 4 speed/1964 Vert!
So here the deal
1996 LT-1 ( Duh ) coupe Auto...

( Buddy form the parts store )

All the error codes/ Module accesses down from 1.4 work but
4.1 PCM
7.1 RTD
9.1 ABS/CTS

Cannot be accessed... the dash will not let you get down to those levels.

Now all the straight up stuff has been done

And the car fires right up

BUT as far as the CCM is concerned the other modules do not exist!

NO error codes at all!

Just no access.. Now all the tan lines for the serial busses check out.. and the modules have proper ground & power.

1) If a module does not exist on the serial line does it shut it off from the CCM?

2) Is there a serial line junction block ( like in a 97) in the 96?



REALLY SKUNKED ON THIS ONE!

Vig!
 

WhalePirot

Well-known member
Joined
May 9, 2002
Messages
2,942
Location
SoCA
Corvette
1984 White Z-51/ZF6-40/Shinoda body
Sounds like a good candidate for the pay-as-you-go Corvette call-in line.
 

vigman

Motor head!!!!
Joined
Feb 13, 2001
Messages
3,471
Location
Valencia, CA,USA
Corvette
88 Convert ( SOLD ) /1973 coupe 4 speed/1964 Vert!
Well I thought this problem will be difficult..

This one I think would be a good head scratcher for Gordon........

Well diving back into the shop manuals...

Maybe PAUL... HEY C4C5 HELP!!!!!!




Vig!
 

vigman

Motor head!!!!
Joined
Feb 13, 2001
Messages
3,471
Location
Valencia, CA,USA
Corvette
88 Convert ( SOLD ) /1973 coupe 4 speed/1964 Vert!
Collecting ECM info here DTC's

http://www.obdii.com/codes.asp

Scott If your reading this thread.... I will collect more and HOPEFULLY someone will chime in as well


Vig!
 

vigman

Motor head!!!!
Joined
Feb 13, 2001
Messages
3,471
Location
Valencia, CA,USA
Corvette
88 Convert ( SOLD ) /1973 coupe 4 speed/1964 Vert!
And this CCM DTC

Old Post.... should be same for 96

How to get at your DTC's

To get to your on board diagnostics....

Piece of paper & pencil at the ready

Key on ( engine off )
press RESET to get any warnings away ( Low fuel etc.)
Press & hold OPTIONS
While holding OPTIONS press FUEL 4 times within 10 seconds

This will start automaticly scan through your
trouble codes, system by system ( or module )
and report back what it finds.

After Auto scroll thru the system parks itself into Manual diagnositcs. ( In case you weren't a fast enough writer)

Fuel =button #1= Previous DTC
Gauges =button #2= Next DTC
Trip =button #3= Prev.System/module
Options =button #4= Next System/module
Eng/Met =button #5= Exit DiagnosticsReset =button #6= Clear DTC code

To clear DTC's
Select system/module
hold Reset for a few seconds
And see if that wipes the error..If not
you really have a problem and not a false trigger.

To get out
Hit button #5 or key off

Hope this helps
Mike
 
B

Black Ice

Guest
Sounds like a bad computer. They do have an 8 year 80k mile warranty from GM so its covered.
 

vigman

Motor head!!!!
Joined
Feb 13, 2001
Messages
3,471
Location
Valencia, CA,USA
Corvette
88 Convert ( SOLD ) /1973 coupe 4 speed/1964 Vert!
More Info

The CCM & ECM are NEW and touted to be flashed correctly ( for matching VIN ID)

This is a weird one.....

I'm LEANING CCM recieve port is non functional

OR wrong CCM for Vette It's kinda weird

The SIR system is the only one that reports an error code when unplugged

all the others are either NOT being accessed

OR

The comm protocol is wrong.... maybe like a Camaro CCM not Vette..

BUT

the thing was doing the SAME things with the Orig ECM/CCM...

AND

The owner has buzzed out all the Serial data line for contunity & shorts to ground... and reports they are FINE!

SO

THINGS ARE FUNKY AT BEST


This all started when the car dropped the 3/4 gear select... it wouldn't go!


and it's been downhill from there.


Poor Scott ( The owner ) has been tearing the car apart for 6 weeks... to no avail!


So that's the deal....


Vig!
 

Rabbit

Well-known member
Joined
Dec 19, 2001
Messages
956
Location
sonoma ca usa
Corvette
2004 C5 coupe, MSGM & 2014 Cad SRX Crystal red
Try search on the web for OBD II. There used to be a couple of forums that were very active. Might be worth a try.
 

vigman

Motor head!!!!
Joined
Feb 13, 2001
Messages
3,471
Location
Valencia, CA,USA
Corvette
88 Convert ( SOLD ) /1973 coupe 4 speed/1964 Vert!
Been there

But the info is pretty generic......

I need some Vette specific info.....

Help C4C5 hallllppppppppp!

May DAY!

Will be pouring over books this weekend ( Sunday ) when the owner drops em off!

Vig!
 

c4c5specialist

Technical Advisor
Joined
May 29, 2001
Messages
3,682
Location
New Haven, Ct. USA
Corvette
Nope, but someday.
Hi there,
Was I paged???????:hb
Anyway, first off, are you getting a SYS from the LCD display???
Second, if you can start and run, then you know for a FACT that the CCM and PCM are communicating, as your Passkey fuel enable signal has been transmitted by the CCM, and received by the PCM. If you serial data line was corrupted, you would NOT be able to start the vehicle.
Just remember, 96 is a whole new ball game as compared to the earlier models.
What do you mean dropped the 3.4 select????????
What exactly is NOT fuctioning??????
Do you have a check engine light??????
Please remember, that 1.4 is only for CCM outputs NOT inputs.
I am offline, till further notice, as my puter crapped it again.
I guess I am not computer friendly, LOL.
I will check again when I am at work on Monday.
Besttoyou, and please keep me posted, c4c5:hb
 

vigman

Motor head!!!!
Joined
Feb 13, 2001
Messages
3,471
Location
Valencia, CA,USA
Corvette
88 Convert ( SOLD ) /1973 coupe 4 speed/1964 Vert!
Paul....Thank Kerist

Ok

Now mind you...I have not physically see this car.. or any of it's component parts.. So it's Ouiji time!

NO SYS indication ( Oh yes it get's weirder )

I realize a 96 is a whole new can O worms... that's why I'm calling in for backup!
( Blub-Blub... two fingers up)

The CCM & PCM are in fact talking.

The SES (MIL/ Check engine light ) Does function.

It goes on... then off when car fires....

NONE OF THE OTHER IDIOT LIGHTS COME ON
ABS-SIR-ETC.......

( Note here... the owner states.. there is an "aftermarket looking wire" jumped between the Batt light and the SES light on the back of the DIC panel)

The ONLY code that he can pull
( Via the dash)

P-661

Which has to do with the MIL ( SES ) light.

Note here AGAIN
You cannot access anything PAST1.4

You push the button...nothing happens... even in AUTO diag!

Like the module THINKS that it did all the things it has to do!

You cannot get to 1.7 / 1.9 /4.1 etc

NO ERR display... it thinks it's happy!

He WAS going to drop the books off today... but the Boss ( His wife ) Has commited him to other pursuits....

Now the way I understand it....

The car shifts.....

Reverse OK
Neut OK
1st OK
2nd OK

and it's stuck there... no 3rd no OD


Poor Scott ( The owner ) Week 6 and he's NOT happy.

ANY LIGHT AT ALL WOULD BE A GOOD THING


So sorry about your PC problems.....

Wish I was there to return the favor!!!!


THANK YOU!

Vig!
 

vigman

Motor head!!!!
Joined
Feb 13, 2001
Messages
3,471
Location
Valencia, CA,USA
Corvette
88 Convert ( SOLD ) /1973 coupe 4 speed/1964 Vert!
More Info ( Tranny )

So the seal WAS blown/going. The complaint was

You had to ROMP the car in second to have the engine rev's high enough to get 3rd to engage ( 4500 rmp ish ) once you dropped down in revs... the more 3rd became like neutral.. and O/D was nowhere to be found.


Scott will come by Tuesday and I will try to get to his house for a bit to get MORE info on the electrical side.

Thanks again for your help Paul!!!!!

How's the computer?

Vig!
 

69MyWay

Well-known member
Joined
Jul 3, 2001
Messages
4,364
Location
Auburndale, Florida
Corvette
1969 Killer Shark
This is some strange stuff here. It is hard to even follow for sure to tell what the problem is, but is sounds aggravating.

Okay, way different car but......

When I did the foolish OBDII 1997 complete electrical and mechanical swap into my 1992 GA, I had a strange problem pop up. It worked great at first, then did not want to go into overdrive, and would toggle back and fourth. I attempted to access the systems all I could, but was unable to get a good read. (I had not yet purchased the OBDII scanner).

I took it to a local trans shop and he hooked it to a snap on device. Come to find out, when I was cleaning the 97 donor engine, I got the gear shift switch (park neutral) wet and it was shorting out. The moisture in there was back feeding and causing all kinds of crazy problem.

After a new switch, and cleaning of the lower end connectors, the car is happy, computer is happy, and I am happy to put it in service and quit fooling with it.

So, I guarantee that I am a mile off here, but you never know! Look at the switch (park/neutral), and check all the lower end connectors for moisture/etc. You want to get an official code scanner as the car just may not be letting itself go into full diagnostic mode, and see what happens.
 

vigman

Motor head!!!!
Joined
Feb 13, 2001
Messages
3,471
Location
Valencia, CA,USA
Corvette
88 Convert ( SOLD ) /1973 coupe 4 speed/1964 Vert!
Chris...

We will check that as well......

The tranny HAS to come out.. so your sugesstion is on the list.

The ODD thing is the scan codes we cannot access from the DASH.... we gave up on the outboard scanner.


More to follow today.

Thanx,


Vig!
 

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