81 wiring ?
Thread Starter
Racer
Joined: Oct 2013
Posts: 251
Likes: 0
From: SAN ANTONIO TX
81 wiring ?
The PO, Bubba, pulled the original crossfire motor from this car and put in a L48. I've posted on here previously about the starter wiring and have received several comments on how to connect the starter but, If the computer is no longer used, and if I am able to find the "purple" wire, will it still work? Not sure what power etc passed thru the computer and needs to be rewired to operate.
SO, if you have done this swap or can provide info on what wiring/rewiring needs to be done to start the car, pls let me know. Starting with the starter wiring as mentioned above.
THX
SO, if you have done this swap or can provide info on what wiring/rewiring needs to be done to start the car, pls let me know. Starting with the starter wiring as mentioned above.
THX
Le Mans Master
Joined: Oct 2006
Posts: 7,123
Likes: 433
From: Gladstone MO
C3 of Year Finalist (appearance mods) 2019
The purple "start" wire has no connection to the ECM that I'm aware of. I don't think GM used the VATS system in '81.
Should be a pretty simple install since the ECM in the early years was just for engine control. Since the crossfire has been dumped, you'll need to find out if the distributor still has the 7 pin module and all that wiring, the knock sensor, and the O2 sensor. GM used the ECM to control ignition timing and did that with the 7 pin module and wiring. The fuel pump for the crossfire was in the tank and there was a relay that ran the pump for 10 seconds whit key on, then an oil pressure switch to turn the pump back on for run.
Should be a pretty simple install since the ECM in the early years was just for engine control. Since the crossfire has been dumped, you'll need to find out if the distributor still has the 7 pin module and all that wiring, the knock sensor, and the O2 sensor. GM used the ECM to control ignition timing and did that with the 7 pin module and wiring. The fuel pump for the crossfire was in the tank and there was a relay that ran the pump for 10 seconds whit key on, then an oil pressure switch to turn the pump back on for run.
Thread Starter
Racer
Joined: Oct 2013
Posts: 251
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From: SAN ANTONIO TX
here are a couple of pics of purple wires I found in the engine bay. One with a plug seems like a dead end, it comes from the harness to the plug. As you can see both harnesses are unplugged. I think they are for AC.
The other purple wire comes to another harness. It appears to go thru the firewall in the wire loom but not positive. Is there a way to correctly ID the "purple" wire?
Thx
The other purple wire comes to another harness. It appears to go thru the firewall in the wire loom but not positive. Is there a way to correctly ID the "purple" wire?
Thx
Le Mans Master
Joined: Oct 2006
Posts: 7,123
Likes: 433
From: Gladstone MO
C3 of Year Finalist (appearance mods) 2019
Your top picture is the connector for the heater fan. THe second one is the connector for the fan speed resistor.
The harness for the starter is plugged into the harness that runs across the firewall behind the distributor. There is a 6 way connector, rectangular in shape that is usually white. The normal spot for it is just to the right of the distributor but inboard of the hi blow relay. In the catalogs, it's listed as "Starter Extension Harness". IT will have the power feed wires (2 ea), the purple "start" wire (it has a white stripe), and a ground wire.
The 2 power wires have ring terminals that will fit over the battery post on the starter and have fusible links within 6" of the end. The start wire is 10 gauge, and has a ring on the end of it that is for a 3/16 stud. The ground is about a 16 gauge wire with a ring for a 3/8 bolt on it.
The harness for the starter is plugged into the harness that runs across the firewall behind the distributor. There is a 6 way connector, rectangular in shape that is usually white. The normal spot for it is just to the right of the distributor but inboard of the hi blow relay. In the catalogs, it's listed as "Starter Extension Harness". IT will have the power feed wires (2 ea), the purple "start" wire (it has a white stripe), and a ground wire.
The 2 power wires have ring terminals that will fit over the battery post on the starter and have fusible links within 6" of the end. The start wire is 10 gauge, and has a ring on the end of it that is for a 3/16 stud. The ground is about a 16 gauge wire with a ring for a 3/8 bolt on it.
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Melting Slicks
Joined: Nov 2005
Posts: 3,323
Likes: 142
From: Green Valley Arizona
I'm confused here....an '81 did not have throttle bodies, it had the E4ME carb. So which do you have an '81 or an '82?
Normally a purple wire is used in the starter interrupt circuit used for the clutch interlock on a manual trans and I think the PARK position for automatics. This relay is also used in the thief deterrent circuit to disable the starter as well.
If the starter solenoid is not getting +12V when the ignition switch is turned to START, then need to find-out where the break is. Could be the ignition switch itself or the starter interrupt relay. Oh and this relay is located under the center console, just in front of the gear selector.
If you need a picture, I have my '81 apart at this time. Let me know.
Normally a purple wire is used in the starter interrupt circuit used for the clutch interlock on a manual trans and I think the PARK position for automatics. This relay is also used in the thief deterrent circuit to disable the starter as well.
If the starter solenoid is not getting +12V when the ignition switch is turned to START, then need to find-out where the break is. Could be the ignition switch itself or the starter interrupt relay. Oh and this relay is located under the center console, just in front of the gear selector.
If you need a picture, I have my '81 apart at this time. Let me know.
Thread Starter
Racer
Joined: Oct 2013
Posts: 251
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From: SAN ANTONIO TX
Pic
The car is a 81 w a swapped in L48. I posted previously abt sparking while connecting battery. Currently the starter is wired like this:
pos from batt to lg lug on starter
Red 10 ga from starter to lug in batt compartment
Blk from lug on starter to gnd.
The po wired this up and trying to figure out correct way
Thx
pos from batt to lg lug on starter
Red 10 ga from starter to lug in batt compartment
Blk from lug on starter to gnd.
The po wired this up and trying to figure out correct way
Thx
Melting Slicks
Joined: Nov 2005
Posts: 3,323
Likes: 142
From: Green Valley Arizona
Swapping in an L48 in place of the original L81 engine is nothing; only real difference was that the L81 had the CCC system. So as along as the complete L48 was dropped-in complete with distributor and carb, should not be a problem. Although there will be quite a bit of extra wiring in the engine bay and the various emissions components will probably not work....if present.
Now regarding the wiring:
Positive cable from battery goes to the large terminal on the starter. Also here are a couple of wires that are fuseable links that lead off to power the car.
Blk from lug on starter to gnd....This should not need to be there. The starter is bolted to the block. There should be a large wire from the block directly to the frame.
The Red 10 ga from starter to lug in bat compartment is also not needed....unless this is some type of disconnect or perhaps to power a large audio amp that was in the back at sometime.
Now regarding the wiring:
Positive cable from battery goes to the large terminal on the starter. Also here are a couple of wires that are fuseable links that lead off to power the car.
Blk from lug on starter to gnd....This should not need to be there. The starter is bolted to the block. There should be a large wire from the block directly to the frame.
The Red 10 ga from starter to lug in bat compartment is also not needed....unless this is some type of disconnect or perhaps to power a large audio amp that was in the back at sometime.
Thread Starter
Racer
Joined: Oct 2013
Posts: 251
Likes: 0
From: SAN ANTONIO TX
But the purple wire would still be needed, correct?
Thx
Thx
Swapping in an L48 in place of the original L81 engine is nothing; only real difference was that the L81 had the CCC system. So as along as the complete L48 was dropped-in complete with distributor and carb, should not be a problem. Although there will be quite a bit of extra wiring in the engine bay and the various emissions components will probably not work....if present.
Now regarding the wiring:
Positive cable from battery goes to the large terminal on the starter. Also here are a couple of wires that are fuseable links that lead off to power the car.
Blk from lug on starter to gnd....This should not need to be there. The starter is bolted to the block. There should be a large wire from the block directly to the frame.
The Red 10 ga from starter to lug in bat compartment is also not needed....unless this is some type of disconnect or perhaps to power a large audio amp that was in the back at sometime.
Now regarding the wiring:
Positive cable from battery goes to the large terminal on the starter. Also here are a couple of wires that are fuseable links that lead off to power the car.
Blk from lug on starter to gnd....This should not need to be there. The starter is bolted to the block. There should be a large wire from the block directly to the frame.
The Red 10 ga from starter to lug in bat compartment is also not needed....unless this is some type of disconnect or perhaps to power a large audio amp that was in the back at sometime.
Race Director
Joined: Apr 2009
Posts: 19,294
Likes: 2,754
From: Charlotte NC
In your photo...the white connector that only has one half of it....the other half goes to your starter. So the large 10 gauge purple wire go to the solenoid and the red wires come from the solenoid and go to this white connector to feed power to your cars wiring. which need to be fusible linked.
I believe the light blue wiring is for an electric fan ( if equipped).
I would highly recommend that you get a factory service manual....there is a wiring diagram that can tell you everything you need...along with a lot more information.
The car more than likely has a theft deterrent system in place (behind the passenger seat, in the rear compartment) and it has a starter enable relay that can cause a problem...which is why you might want to get a manual.
DUB
I believe the light blue wiring is for an electric fan ( if equipped).
I would highly recommend that you get a factory service manual....there is a wiring diagram that can tell you everything you need...along with a lot more information.
The car more than likely has a theft deterrent system in place (behind the passenger seat, in the rear compartment) and it has a starter enable relay that can cause a problem...which is why you might want to get a manual.
DUB
Thread Starter
Racer
Joined: Oct 2013
Posts: 251
Likes: 0
From: SAN ANTONIO TX
Yes Dub, It does have the factory alarm in it. I have not been connecting everything when I put it back together such as door lock connectors, t top alarms and hood switch.
I have a wiring diagram and I know the harness was incomplete but was thinking about pulling a Bubba and tapping into the purple wire at the harness and running it to the starter. If I need the other wires from the harness , I will find one to buy.
Thx
I have a wiring diagram and I know the harness was incomplete but was thinking about pulling a Bubba and tapping into the purple wire at the harness and running it to the starter. If I need the other wires from the harness , I will find one to buy.
Thx
Race Director
Joined: Apr 2009
Posts: 19,294
Likes: 2,754
From: Charlotte NC
For what it is worth.
That white connector in you photo that goes down to the starter was something GM added for ease of assembly. I can tell you i have seen and repaired many due to resistance in this connector due to all of the current and high amps that pass through it. SO...if the terminals are not CLEAN and TIGHT when they join...you can have a beginning of resistance and thus it will heat up and can melt. I have seen it many, many times. Also...this IMPORTANT connection is NOT protected from water and dirt...which can also cause a problem in the future...unless it is filled up with a compound that repels dirt and water.
I have cut out this connection and soldered and shrink wrapped the wires together so no issues will occur. It is NOT FACTORY...but some of my customers do not care about everything being original GM...especially when some design change ideas are not the best in the long run.
DUB
That white connector in you photo that goes down to the starter was something GM added for ease of assembly. I can tell you i have seen and repaired many due to resistance in this connector due to all of the current and high amps that pass through it. SO...if the terminals are not CLEAN and TIGHT when they join...you can have a beginning of resistance and thus it will heat up and can melt. I have seen it many, many times. Also...this IMPORTANT connection is NOT protected from water and dirt...which can also cause a problem in the future...unless it is filled up with a compound that repels dirt and water.
I have cut out this connection and soldered and shrink wrapped the wires together so no issues will occur. It is NOT FACTORY...but some of my customers do not care about everything being original GM...especially when some design change ideas are not the best in the long run.
DUB