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1981 ECM question

vigman

Motor head!!!!
Joined
Feb 13, 2001
Messages
3,471
Location
Valencia, CA,USA
Corvette
88 Convert ( SOLD ) /1973 coupe 4 speed/1964 Vert!
The check eng. light on my friends 81 is dead.
1) Who has a factory schematic?
2) The check engine light driver module is located where?
3) The 5 pin connector ( under the ashtray ) It states to jump pins d & e but nothing happens ( I'm assuming the key needs to be on for this)
4) the bulb is good and there is 12 volts to the circut.

So brave one's
HELLLPPPPP!

Mike
 

Nut

Well-known member
Joined
Oct 15, 2000
Messages
890
Location
Bowie, MD
Corvette
Vette-less for now
Mike, I have a full schematic at home but I'm at work now. If you have no satisfactory answers by this evening I'll dig it out and have a look. Stay tuned.

......... Nut
 

vigman

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

Standing By........
Mike
 

Yoda

Well-known member
Administrator
Joined
Oct 12, 2000
Messages
4,885
Location
Amarillo, TX
Corvette
1981 UL5
Mike,
I didn't have a chance to check in last night, I was having computer problems at home.. :mad

I'll get back to you tonight once I have a chance to take a look at the schematics and wiring diagrams..
 

Nut

Well-known member
Joined
Oct 15, 2000
Messages
890
Location
Bowie, MD
Corvette
Vette-less for now
Mike,

I've got my shop manual at work today and I'm going to try and get the whole schematic scanned into MSWord. If it doesn't come out I'll mail you the copies. Send me an Instant Message with your home address and I'll get it out this weekend. It's REAL hard to follow that particular run. Took a while to even find it in the schematic. Sorry it took so long to respond.

......... Nut
 

vigman

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

Wilco!

Mike
 

vigman

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

You DA MAN!

Got the package last night

THANKS SOOOOO MUCH

Now if I can get out of work I can help my poor british buddy.'


MIKE
 

RonG

Member
Joined
Dec 12, 2001
Messages
8
Location
San Ramon, CA USA
Corvette
1981
Vigman,

Have you got things working yet?

FYI - On my 1981 I kept getting a code set. Turns out the diode in the EGR solenoid circuit shorted out and blew the driver chip in the ECM.

Since the EGR parts are no longer available, I hand repaired the old one.

After running all tests and still getting the ECM code set, the shop manual states to replace the ECM. I it with a rebuilt unit (about $90) and all is well.
 
R

Rob81

Guest
Were you able to get another PROM chip for your new ECM?Didn't you state before that your Prom was shorted out by your EGR problem. I'm probably wrong, but I didn't think that EGR was related to the ECM electrics. I thought that the ECM was only regulating the M/C Solenoid, TPS, Coolant Temp,.
I'm having some drivabilty problems, getting codes. My mechanic has looked the car over twice and can only think that it is ECM and/or Prom chip. I hate to buy and install a new ECM only to have it shorted out by something else. Cars???
 

RonG

Member
Joined
Dec 12, 2001
Messages
8
Location
San Ramon, CA USA
Corvette
1981
Rob,

You stated: . I'm probably wrong, but I didn't think that EGR was related to the ECM electrics. I thought that the ECM was only regulating the M/C Solenoid, TPS, Coolant Temp,.

If you look in the 1981 Shop Manual pages 8A-82 & 8A-83, you will see the ECM diagram and all that it controls.

As for the EGR, there is a relay controlled by the ECM that controls vacuum going to the EGR valve.

One other thing to remember, the ECM has two functions:
1) Monitor certain signals
2) Control certain functions

The ECM monitors the TPS and Coolant Temp, but does not control them.

Controls:
=======
AIR control valve
AIR switch solenoid
Ignition module bypass
Spark timing
MCC
EGR
Torque Converter (automatic tran only)

Montiors:
=======
Vacuum sensor
TPS
O2 sensor
Dist pulse ref
Coolant temp
Vehilce speed (automatic tran only)
Park/Neutral Switch (automatic tran only)

I think that's everythin.

As for your other questions on the PROM, that must have been someone else posting.


Regards,

RomG
 
R

Rob81

Guest
Thanks..It sounds like I need to find one of those shop manuals.
 

Yoda

Well-known member
Administrator
Joined
Oct 12, 2000
Messages
4,885
Location
Amarillo, TX
Corvette
1981 UL5

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