Help needed with troubleshooting saftey switch
 

When I turn my key to the On position my fuel pump begins to run. From what I understand the pump should not run until the starter has been engaged or if the air plate is lifted up. I am trying to figure out why mine is not reacting as expected. Where do I begin troubleshooting? Could the switch on the air plate be bad or out of adjustment? If so, how do you get to it and how do you test it?
I’m looking for step by step things to check for.
Thanks
Rick

On my 75 the fuel pump turns on when the ignition switch is turned to "on" as well. I think this is a midyear design. I thought they changed it in 77 but things were changing mid production year as well. I thought they changed this when they went with the front fuel pump in 76. But I'm not sure. Was your 77 converted or is it one of the 77 3.0 cars? Where is the fuel pump?

hi..have you had your 911 in some kind of service place?
if this happens it could be that you safety plug on your sensor plate is disconnected .this a safety device in case you turn the car on roof .It will stop the fuel pump.So when the plug is off the pump will run with the key on...
here different model of 911 but location same--check it..to start with..
ivan
http://img.pccreation.net/photos/201704022327109260.JPG

It is a 77 that had a 2.7 and I installed a 81 3.0 in it. From what I understand the the 76 and later had a saftey switch on the air plate and it would shut the fuel pump of when it is in the rest postion. The power would come from the starter until the plate was lifted by air intake. Mine is acting like the switch is engaged or the plate is up and that is why i want to test it to see if that is my issue.


Thanks
Rick

The green plug is plugged into it. It appears to be two wires in the plug, where do they go to?

You plug is plugged in as you are saying and with the key on the fuel pump runs?

Yes

ok i see you open another thread regarding the car was sitting for a while.What else did you do on it.
Any works on wiring?I would start with the basics fuel pump fuse and relay...
Ivan

Air flow sensor switch........
 

Rick,

Check if the AFS electrical plug is connected at the backside of the AFM (air flow meter). You could find out if the electrical plug is connected by using your fingers to feel it or use a small mirror. If it is connected then you could do the following test.

a). Remove the FP relay and locate terminal #85 on the relay socket. You could test terminal #85 either using continuity test between #85 and the sensor plate. Or use a 12-volt TL (test light). I find the TL more convenient and practical for this kind of test.

Terminal #85 is a ground connection for the FP relay that goes to the driver-side terminal or pin of the AF switch. The passenger side terminal of the AFS switch is connected to the AFM body and the wire (brown) goes to D- (alternator).

If you decide to use a 12-volt TL which I strongly recommend, use terminal#85 (FP relay socket) as your ground source. Connect the alligator clip of the TL to a known 12-volt source or use the positive pole of the battery. With the TL connected to a 12-volt source, place the tip of the TL to any known good ground for test. Then test terminal #85. It should not lit up (NORMAL). If it does lit up, you got a PROBLEM.

Either the electrical plug is disconnected or the switch is defective.

b). AFS switch test and adjustment. Will do this later after you have done the above test.

Keep us posted.

Tony

Correction/edit:

The highlighted text above should read as: "It should lit up (NORMAL). If it does not lit up, you got a problem".

I tested 85 and it did not light up. So what is next step?

Thanks
Rick

Test result.......
 

Rick,

The TL should light up. Make sure you have tested the TL using a known good ground source before using terminal #85. If terminal #85 is not grounded;
a). The electrical plug to the AFS (air flow sensor) switch could be unplugged or defective.
b). The brown wire between terminal #85 and the driver-side pin at the plug or connector is open.
c). You need to test the continuity between terminal #85 and the AFS switch.
d). The sensor plate is misaligned and not coming in contact with the ground contact.
e). Everything OK except the passenger side terminal (AFS) is not grounded.

These are the conditions you have to test and verify. One step at a time. Have you checked if the electrical plug to the AFS switch is connected or not? You did not mention anything about it. Keep us posted.

Tony

The switch is plugged in as I replied in post 7. In your first post you mentioned that it should not lite up, and if it did then I have a problem. That might have been a typo. I will check the rest of your suggestions and report back . I am doing this with the key in the off position, is that correct? By the way , I checked all of the other ports and they all lite up.

Rick

When you installed the '81 which engine harness did you use?
The air flow switch is wired differently in the '77 than the '81.
The '77 has a brown with black single plug below the 14 pin connector at the fuse panel that is for the safety switch. The single wire female plug that goes to it, comes off the '77 engine harness just before the female 14 pin connector.
The safety switch wire in the '81 normally goes to the 2 wire "T" connector by the CDI box.

Correction.......edit post #9.
 

Rick,

There were mistakes (typo) in the last 2 sentences above (post #9). It should read as:

"It should lit up (NORMAL). If it does not lit up, you got a problem"

My wife was calling me for dinner and quickly posted it. I had it backward. My mistake.

To recap it, the reason the FP is running with the ignition switch @ ON position could be caused by:

a). A defective FP relay.
b). Terminal #85 is not grounded.

Your test has shown that terminal #85 is not grounded. This is the problem. It should be grounded. The culprit could be one of the following:

a). Terminal #85 has a loose or open connection to the AFS (driver-side) pin or terminal. A continuity test has to be done.
b). The AFS switch is misaligned and not getting a good contact with the sensor plate.
c). The connection from the passenger side of the AFS terminal (plug/connector) going to D- (alternator) is loose or open.

Any of the above condition will cause terminal #85 to loose ground contact.

Tony

Tony, unless he swapped the wires on the body or harness going from a '77 to an '81 engine harness, the safety switch won't work.
OP hasn't replied to my post as to how the wiring was adapted.

Correct......
 

Rick,

The SC engine wire harness has a white 2-wire connector close to the 6-pin CDI plug. Take a look if this white connector is connected to the chassis wire harness. One is red coming from the ignition switch and the other brown/black or brown. This brown wire from the chassis wire harness is connected to terminal #85 (FP relay socket).

The other side (brown) for the engine harness goes to the AFS connector (driver side 1-2-3). If you post a picture of the engine wire harness with the white connector will be very helpful. Thanks.

Tony

Brown/black on '77 body harness comes out below the rear 14 pin connector.
Tach and CDI power are in the "T" connector for '77
Refer to my earlier posts.
Need to know how the engine swap wiring was done.

Find the single brown/black wire below the 14 pin connector, ground it and see if the fuel pump stops.

'77S wiring...........
 

Dennis,

I don't understand why you said that the white plug connection for the AFS switch is different from '77 to those of the SC's? I will take another look at the white connector from the '77S chassis and inspect the wires. Here is the picture of the engine wire harness on the '77S:

http://forums.pelicanparts.com/uploa...1491236268.jpg

Below is the picture of the white connector from the engine harness that I got from you.
http://forums.pelicanparts.com/uploa...1491236365.jpg

Shouldn't this be just a direct plug in to work? You are the harness guy and got all the experience about these harnesses. I just took the picture this morning and have not really look deeply into the details. Please advise. Thanks.

Tony

Tony, look at your first photo. The wires going to the T plug are red and purple/black. They are CDI power and tach signal.
The 78 and newer body harnesses have red and brown/black (or brown/red) for CDI power and safety switch.
The '76 and '77 have the safety switch Brown/black wire as a single plug below the 14 pin connector.

Take a good look at the schematics for the '77.
https://www.dropbox.com/sh/jxno8o6qae3roun/AADW1qBcRc53LoEG0TPbRwFva?dl=0

Dennis and Tony,

Sorry I have been MIA , Work has me busy and out of town for the next 2 or 3 weeks. I did have time this morning to check from 85 to the pin on the rear AFS and there is a break somewhere. I just seen all of the post since my last post and I will tried to find time to verify the connections at the rear. I need to go back and check my notes when I did the swap but I did use the harness from the updated 81 3.0L. I believe that I spliced it into the body harness . Again, I will try to check it when I get home tonight. I fly back out of town Sunday for two more weeks on the road.

Thanks
Rick

AFS switch update
 

I am back in town for a few days so I was able to spend some time on it and here is what I know.

The brown wire coming from pin 85 on the FR to the rear is not plugged into any thing.
http://forums.pelicanparts.com/uploa...1492277298.jpg


And the wire(s) , white plug, coming from the AFS switch which I found on the 81 3.0.L harness is below. I have the red wire going to a switch 12 Volts and the brown wire to nothing.

I checked the AFS with an ohm meter and it checks out good as expected when I lift the plate.
Could I connect the brown wire on the white plug below to the single wire in the above picture? Then leave the red wire connected to the 12 volt switched or do I need to connect it to some where else?
http://forums.pelicanparts.com/uploa...1492277655.jpg

Thanks
Rick

Without rereading the entire threat, let me offer this.

Assuming the wire in your first picture is from terminal 85 of the FR, it needs to be connected to the AFS switch wire.

Before doing that, however, put a test light on the white terminal connector to the brown wire to check if it is grounded. Then, lift the sensor plate in the intake. Does the brown wire lose ground connection? If so, connect the wire from 85 to it. If not, do not connect to it as it is a constant ground and the relay will never cycle into the running position.

Ok, I will try that , but meantime what should the red wire from the AFS be connected to? Will any switched 12 volt work?

Air flow sensor switch........
 

There is no red wire going to the AFS switch. The switch has two (2) brown wires. The orientation of the 3.0 liter SC AFS switch is as follow:

Driver side (cyl.1-2-3) has brown/red wire going to the wire plastic connector (engine side). And the chassis side for this wire (brown/black) goes to FP relay terminal #85.

Passenger side (cyl. 4-5-6) has brown wire going to alternator @ D-.

Use a test light or continuity tester for troubleshooting or identifying these wires. This is basic electrical 101.

Tony

White electrical connector for AFS switch and CDI.......
 

Rick,

This is the picture of the white electrical connector for the engine harness built by Dennis P. Take note of the wire color (chassis side) and from the engine harness.

http://forums.pelicanparts.com/uploa...1492305844.jpg

Engine harness:
Red wire @ white connector goes to CDI @ terminal #15.
Brown/red (actually it is pink/red; ask Dennis) @ white connector goes to AFS switch pin (driverside or cyl.1-2-3).

Chassis harness:
Red wire @ white connector goes to ignition switch @ terminal #15.
Brown/black wire @ white connector goes to FP relay socket @ terminal #85.

NOTE: The above is for an SC engine and chassis. Since you are using a '77 chassis, the chassis side would be slightly different as mentioned by Dennis. I have a '77S chassis that I will install this motor (shown in the picture above). But I have not yet looked closely at the chassis. So I will be doing this exact work in a few weeks.

http://forums.pelicanparts.com/uploa...1492305868.jpg

So if you could document with some pictures the location of the brown wire from the FP relay and red wire from the ignition switch would help other readers including myself. My '77S chassis is stored a few miles away from home.

Tony

Engine chasis wiring
 

I will try to say this differently.

This is a picture of the wiring harness on the 3.0L engine side. About five inches below the 6 pin CDI plug is a two wire white plug. That plug has a brown wire with what looks to be a small red stripe and a solid red wire. Using a DVM I checked for continuity from the red wire at the plug to the connector that plugs into the AFS on the passengers side (4-5-6) and I have continuity . Then I checked the brown wire on the same white wire to the plug for the AFS drivers side pin (1-2-3) and I have continuity. So I am very confident that the white plug and wires below enter into the engine wiring harness and terminate at the green AFS plug.

Note: I replaced my CDI with a MSD AL6 some time back. The red wire that you see spliced into the red wire at the white plug goes to a switched 12 Volt source and to the MSD to provide switched 12 Volts.
http://forums.pelicanparts.com/uploa...1492368709.jpg


Then the picture below is the rear area of the fuse and relay mounts. I unplugged the 14 pin connector so that you can see the single brown wire with a black plug on the end. This is original to the 77S and it goes to the pin 85 on the FR.

Note: In order to make my AFS work again I was trying to confirm:
1. IF I were to connect the brown wire seen in the above picture coming out of the engine wiring harness which is from AFS pin on drivers side (1-2-3 cylinders) to the brown wire seen in the picture below that terminates at pin 85 FR, would that work?
2. Should I connect the red wire in the above picture which is the AFS passenger side (4-5-6 cylinders) to a switched 12 volt source as I currently have it?

Tony , you mentioned connecting this to the Alternator @D- , but I have no idea where to start to find this wire or connection and I don't want to rip my wiring harness open and start pin poking my wires to find it. If I need to connect this wire there instead of the switched 12 volts, could you please at least give me a hint to where I could find this wire to Alternator @D-????

http://forums.pelicanparts.com/uploa...1492370309.jpg
I don't mean to sound frustrated , but what I have and what is in the pictures that you posted don't match and I don't know if it is because they are different years modules or if I am looking at the wrong plug on my end.
Thanks for any help
Rick

You need to confirm if the brown/red stripe wire in the double white connector loses ground when you lift the air sensor plate in the intake. That is the key to the safety switch/relay circuit--the loss of a ground to terminal 85 when the air flow sensor plate raises from its stop.

Run a quick test to see if the brown/red stripe wire loses ground. Use a test light with the wire as the ground connection. Lift the sensor plate and if the light goes out, that is the wire to connect the lead to terminal 85.

I tested it and it does lose ground when the plate is lifted. So I will connect this brown wire to the single wire that goes to the pin 85 FR. That leaves the other red wire. Does it matter where it connects to? Tony mentioned the Alternator @D- , but I don't have a clue where to find this connection or wire to splice into

Thanks
Rick

12-volt power.......
 

Rick,

What ever you do, DO NOT supply power (12 volt) to the AFS switch!!!! The AFS switch is a ground contact with BROWN wires. I have to go over and re-read your post about the RED wire going to the AFS switch (?).

Summary:
FP relay terminal #85 wire goes to the white connector (chassis side). The engine side white connector with brown/red wire goes to the pin (cyl.1-2-3 side) at the switch. The other pin @ cyl.4-5-6 side goes to D- (alternator).

Consider talking to LJ. He could explain it better than anyone around. I discovered the anomaly in Dennis engine wire harness with a reverse wire installation. Which would be no problem for engines with plastic fuel lines but would cause a malfunction for engines with metal fuel lines ('81~'83) SC USA models. I believe he has corrected the problem already for the new harnesses.

Tony

Let's see... I have told you what to do, others have steered you all over the place.
This is so simple.
I have built multiple new engine conversion harnesses for exactly what you have.


Connect the brown/black coming out of the body harness to the Brown/red coming out of the engine harness in your photo with a jumper to make your flow switch work.
Done.
Don't mess with any other wires.
Sorry, I'm tired and a little grumpy...

Just install the he jumper and give it a try. :)

Yes, do this.... nothing else...

'77S white connector in engine bay......
 

Dennis,

I will be installing an SC engine into a '77S roller pretty soon. The roller is stored away from home and it is raining now in Philly area. In the white plug shown in the picture below has 2 red wires and a black (?) wire.

http://forums.pelicanparts.com/uploa...1492440193.jpg

What is the black wire for? Is this a black wire with violet stripe on it? Thanks.

Tony

Hi Tony,
Yes, the second wire on the '77 2 wire "T" connector, near the CDI, is the tach signal connection.
It is black/purple.
The brown/black air flow safety switch wire is near/below the male 14 pin connector.

SC motor into a '77S chassis.......
 

Dennis,

So to utilize your SC engine wire harness (for white connector) do I need to:

a). Remove the black/violet wire (from the '77S white connector) and install the brown/black from FP relay terminal #85?
b). Connect the black/violet from tach to black/violet of CDI @ TD?

I know that the white connector from engine (using your SC harness) needs two (2) wires.
a). Brown wire from terminal #85 (FP relay socket).
b). Red wire from ignition switch @ 15 to power the CDI.

What do you recommend to your clients when they do this conversion (SC engine to '77). BTW, I got two (2) sets of engine wire harness from you. So I consider myself one of your clients too. Thanks.

Tony

Hi Tony,
Normally I wire the harnesses for the customer so they are plug and play when installing a 3.0 with 6 pin CDI.
You need to Re-wire the 3.0 14 pin female plug to the "77 configuration.
Run the tach wire from CDI to purple black.
Run the brown/red on engine harness to the brown/black single plug.
I just happen to be building a '77 through body harness this week so I can give you a 14 pin male plug layout for the '77 later when I am at home.

Cheers,

3.0 SC engine to '77 S chassis.....
 

.
Dennis,

I have made a chart for the SC and '77S 14-pin connectors in the 90's. However, the '77S chart has not been used as reference yet. If you could provide a copy of your '77S 14-pin would be great. BTW, I will be needing a new set of engine wire harness for a '83 this summer. Thanks.

Tony

'77 male 14 pin pin out:
1. Yellow starter solenoid
2. Green spare for manual trans
3. Green/Black Oil temp
4. Green/Red oil pressure gauge
5. Green/Yellow reverse switch from fuse panel
6. Grey/Brown reverse switch to 6 pin lights
7. Blue/yellow spare on manual trans
8. Brown/white spare
9. Green/White oil pressure idiot light
10. Red/White for WUR, AAR etc. from front fuse panel.
11. Blue alternator light.
12. Blank (no wire)
13. Yellow/Black engine blower motor relay
14. Red from alternator B+ goes to 3 Fuse panel. (Fuse 3)