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81 vett. engine light will not come on with key.

 
richard1061
I love my Chevy Chevette!
Posts: 19
Joined: 12/13
Posted: 12/08/13 02:14 PM

Hi wayne..checked out c to b-7.0, c to 4- 1.9, c to e no wire. 18 no wire. 19-19.2, 3 to 7- nothing. this vet. is a stick.   I found a burnt wire,the pink one the console wore a hole in it. fixed that. put the new ECM in. light comes on,will not go off. jumped for cod, it won't blink. well the light comes on now. I am going to pull the ECM and check the prom.  

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wayne712222
My first time was in a Chevy
Posts: 140
Joined: 10/13
Posted: 12/08/13 02:31 PM

C to B   over 20 ohms  7.0  ohms  air switch.

C to 4  over 20 ohms   1.9 ohms   air divert switch

C to E  over 20 ohms    no wire  

C to 18 over 20 ohms    no wire.. thats STRANGE.. thats the mixture control solenoid..

C to 19 over 20 ohms    19 ohms   EGR solenoid

3 to 7  the coolant temp sensor  OPEN...  this should read the same as the coolant temp sensor... HMM>..

let me dig into the caddy manual and see if i can find more detailed info before you plug the computer back in..

if the prom is incorrectly plugged.. i normally expect a code in the 50s

i identified the circuits above.. disconnect each one..  without wiggling the wire or the harness and see if the test circuit opens..  

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wayne712222
My first time was in a Chevy
Posts: 140
Joined: 10/13
Posted: 12/08/13 02:36 PM

C to B   over 20 ohms  7.0  ohms  air switch.

C to 4  over 20 ohms   1.9 ohms   air divert switch

C to E  over 20 ohms    no wire  

C to 18 over 20 ohms    no wire.. thats STRANGE.. thats the mixture control solenoid..

C to 19 over 20 ohms    19 ohms   EGR solenoid

3 to 7  the coolant temp sensor  OPEN...  this should read the same as the coolant temp sensor... HMM>..

let me dig into the caddy manual and see if i can find more detailed info before you plug the computer back in..

if the prom is incorrectly plugged.. i normally expect a code in the 50s

i identified the circuits above.. disconnect each one..  without wiggling the wire or the harness and see if the test circuit opens..

this shows the components are not shorted that the wiring is..  

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richard1061
I love my Chevy Chevette!
Posts: 19
Joined: 12/13
Posted: 12/08/13 02:37 PM

oh the instruction sheet says make sure all diagnostic test are complete. I can E mail it to you. it doesn't tell you how to do test.  

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wayne712222
My first time was in a Chevy
Posts: 140
Joined: 10/13
Posted: 12/08/13 02:40 PM

i know..  some instructions start with the term..

OPEN BOX..

i posted just above..  copy that or go to the private message link and give me a call..  just to the left of where you log out at..  

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wayne712222
My first time was in a Chevy
Posts: 140
Joined: 10/13
Posted: 12/08/13 02:59 PM

C to B   over 20 ohms  7.0  ohms  air switch.

C to 4  over 20 ohms   1.9 ohms   air divert switch

both of the above should read over 30 OHMs.. please test the harness with the plugs disconnected from the 2 air valves..

the diverter valve should look similar to this..



i hope its the wires.. as this piece is over 500 bucks for an 82 model.  i have to find my older emission catalogs for the 81 part number.. or have you examine your parts for it..

C to E  over 20 ohms    no wire  

C to 18 over 20 ohms    no wire.. thats STRANGE.. thats the mixture control solenoid..

C to 19 over 20 ohms    19 ohms   EGR solenoid

3 to 7  the coolant temp sensor  OPEN...  this should read the same as the coolant temp sensor.

please measure the resistance of the coolant temp sensor.. its possible the computer shorted and sent excessive voltage to it or it shorted to ground and burned out the thermister.. disconnected it should be open.. connected it should be the same as the sensor resistance.. and you will have to move your ohm meter off 200 ohms.. you may have to set it to 200K ohms to get a reading..  

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richard1061
I love my Chevy Chevette!
Posts: 19
Joined: 12/13
Posted: 12/08/13 03:32 PM

C to B 9.4
C to 4 19.4
C to 18 23.5
C to 19 19.2
3 to 7 good on both ends
had to get a magnifying glass.  

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wayne712222
My first time was in a Chevy
Posts: 140
Joined: 10/13
Posted: 12/08/13 03:35 PM

i am working on a chart that i will post here to assist you in checking the wiring harness...

back soon

i am putting voltages and wire colors on it..

81Ccccomputerconnector1 Zpsa1d681ef  

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richard1061
I love my Chevy Chevette!
Posts: 19
Joined: 12/13
Posted: 12/08/13 04:31 PM

air switch is on top? it reads 19.5 reads
bottom valve, air devert? reads 32.o  set on 2k.  

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wayne712222
My first time was in a Chevy
Posts: 140
Joined: 10/13
Posted: 12/08/13 05:17 PM

with the selected devices unplugged..
do they all read OPEN??  Or OL.. on the meter .. they should..

this is with the computer unhooked..

if they do thats good.. then ohm the individual devices..

i see you have done the air valve.. thats better numbers.. i wonder if there is an issues somewhere else..

241B91ab 17F3 49Fa 9F18 22A5656532df Zps54c1d670  

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wayne712222
My first time was in a Chevy
Posts: 140
Joined: 10/13
Posted: 12/08/13 05:28 PM

lets work on the engine coolant temp sensor.. screwed into a water passage on the intake.. with a pair of wires to it.. usually yellow and black.. you might have already changed this. but it should show some resistance...

3 to 7  the coolant temp sensor  OPEN...  this should read the same as the coolant temp sensor... HMM>..

Su102

Code 15 GM Zpsdd4aa4b6

use this last chart.. just for the sensor ranges in the corner  

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richard1061
I love my Chevy Chevette!
Posts: 19
Joined: 12/13
Posted: 12/08/13 05:51 PM

getting late looks tomorrow.  

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wayne712222
My first time was in a Chevy
Posts: 140
Joined: 10/13
Posted: 12/09/13 08:05 PM

CCC 1981 Wontflashcode12 Zps548cb09d


1981Corvettefullfunctionybody Zpsbec14801  

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wayne712222
My first time was in a Chevy
Posts: 140
Joined: 10/13
Posted: 12/09/13 08:40 PM

man... i forgot the corvette ECM was behind the drivers seat..
thats a LONG run of wires..

do you have or can you set up a LONG jumper lead.. so you can unplug everything on both ends..

and run a continuity beep test for each circuit against every other circuit..

there are so many places for that harness to get pinched... shorted out.. cross fed.. insulation to fall off..

i am attempting to work out a chart.. but my new to me..2008 duo core mac lap top. does not run the same programs my older 2002 G4 tower does..

wow... each of the wiring diagrams shows the wires going to different connectors than all the others..

only way to identify the circuits is by wire color.. can you photograph each side view of each connectors.. or just leave them plugged in.. straighten the wires slightly and snap a clear photograph.. i need to see the order the wires go into the connectors..

can you print the diagram that shows the connectors.. and write in the wire colors on your connectors then up load it to photobucket..

but actually.. you will want to print and run Chart 7 above..  let me know what happens...  

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richard1061
I love my Chevy Chevette!
Posts: 19
Joined: 12/13
Posted: 12/10/13 01:09 PM

okay that sounds good. give me some time on that. I got to squeeze in some Christmas shopping.
I got a toshiba lap top windows 8. definitely different.  

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