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Alan L's Avatar
 
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Right - got it. Mark is right. I have been tripped up on this before. In that schematic, the pumps are not running - the front relays are not supplying power to the pumps. The airplate circuit is holding the rear relay open from triggering the circuit. When the airplate opens and breaks that circuit the rear relay reverts to it's 'normal' position and allows the power feed to the front relays. So pulling the plug has same effect.
So when you open the plate you should be breaking the circuit between the two contact points on the switch. If that switch is not closing to make a circuit when at rest (bad contact in sw) then you will have the problem you have now. PITA, but if you can get your multi meter to the prongs/terminals on the SWITCH and check continuity with plate open/closed you may get you answer. If no continuity in any position then that is the issue. Should only be on continuity when plate open. Good luck.
Alan

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83 SC, 82 930 (track) - Stock except for RarlyL8 race headers, RarlyL8 Zork, K27-7006, 22/28 T bars, 007 Fuel head, short 3&4 gears, NGK AFR, Greddy EBC (on the slippery slope), Wevo engine mounts, ERP rear camber adjust and mono balls, Tarret front monoball camber adjust, Elgin cams, 38mm ported heads, 964 IC. 380rwhp @ 0.8bar Apart from above, bone stock:-)
Old 03-18-2018, 09:19 PM
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Quote:
Originally Posted by mooney265 View Post
For right now, I can say for certain there is a ground on just 1-side of the AF Plate PLUG... However, both sides of the PLUG have Ohms to one of the Rear Relay Socket Plugs. Not too sure what that means...


Shannon
You should have ZERO ohms on one side of the plug - ie perfect earth. If the earth side is imperfect (bad earth) same effect as pulling the plug = pumps on.
Alan
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83 SC, 82 930 (track) - Stock except for RarlyL8 race headers, RarlyL8 Zork, K27-7006, 22/28 T bars, 007 Fuel head, short 3&4 gears, NGK AFR, Greddy EBC (on the slippery slope), Wevo engine mounts, ERP rear camber adjust and mono balls, Tarret front monoball camber adjust, Elgin cams, 38mm ported heads, 964 IC. 380rwhp @ 0.8bar Apart from above, bone stock:-)
Old 03-18-2018, 09:25 PM
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Another thing you could do - with the airplate plug - with a small alligator clip is jump the NON - earth terminal to earth - with key on. If the pumps stop then you have found the problem. Bad earth on the other leg of the plug circuit. The sw is just acting as a bridge while airplate is closed.
Alan
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83 SC, 82 930 (track) - Stock except for RarlyL8 race headers, RarlyL8 Zork, K27-7006, 22/28 T bars, 007 Fuel head, short 3&4 gears, NGK AFR, Greddy EBC (on the slippery slope), Wevo engine mounts, ERP rear camber adjust and mono balls, Tarret front monoball camber adjust, Elgin cams, 38mm ported heads, 964 IC. 380rwhp @ 0.8bar Apart from above, bone stock:-)
Old 03-18-2018, 09:37 PM
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look at the diagram,

YOU HAVE A PROBLEM BETWEEN "G" OVER BOOST RELAY PIN 85 AND GROUND.

if you can jumper the pins at the connector to the afm the AFM switch is probably good, not your
problem.

remove the over boost relay. connect a test light to the fuse block in engine back. make sure it lights, then test the 2 pins in the AFM connector, ONE should light the light. if it does, that is the one that goes to ground and that side of the circuit is good., if good then problem is between connector and OB relay. check the relay socket for a loose connection.



the over boost SWITCH has nothing to do with your problem,


if you want to know how it works go to the sticky and look for my post on how the system works.
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Old 03-19-2018, 04:31 AM
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This problem has nothing to do with the overboost switch, it is the air meter plate switch circuit. That circuit operates ass-backwards by using ground to turn the pumps on. If there is a ground fault anywhere in the circuit it will be defeated and the pumps will run when the key is on. You have to find where the ground is, could be a broken or corroded wire, so the circuit must be traced.
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Old 03-19-2018, 06:13 AM
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Quote:
Originally Posted by RarlyL8 View Post
This problem has nothing to do with the overboost switch, it is the air meter plate switch circuit. That circuit operates ass-backwards by using ground to turn the pumps on. If there is a ground fault anywhere in the circuit it will be defeated and the pumps will run when the key is on. You have to find where the ground is, could be a broken or corroded wire, so the circuit must be traced.
Agree.
Not o/boost circuit - it is working as supposed. Pumps running (key On), he pulls o/boost terminal, pumps stop. As they should. That part of circuit is correct. His symptoms are same as if airplate plug is pulled = disrupted circuit to earth. Which would look like a likely bet there is a faulty earth in that leg of the circuit. Which is the sort of thing that would explain why it was OK, then suddenly acting like this.
Alan
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83 SC, 82 930 (track) - Stock except for RarlyL8 race headers, RarlyL8 Zork, K27-7006, 22/28 T bars, 007 Fuel head, short 3&4 gears, NGK AFR, Greddy EBC (on the slippery slope), Wevo engine mounts, ERP rear camber adjust and mono balls, Tarret front monoball camber adjust, Elgin cams, 38mm ported heads, 964 IC. 380rwhp @ 0.8bar Apart from above, bone stock:-)
Old 03-19-2018, 11:24 AM
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So, I was able to get to the switch fairly easily thanks to the easy removal of the K&N. I've attached some pictures...

What I get is 5.88-ish Ohms when closed and when I press down the slightest bit on the air lever, it breaks/opens the circuit.




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Old 03-19-2018, 12:10 PM
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If I am reading you right, that is 5.8K ohm. High resistance. May be the sw, may be you still have a bad earth line on the sw circuit. What you can do is get a wire with small alligator clip - I can't remember which way the plug terminals go - pins or sockets? But take the plug , key on, pumps running, and earth each of the plug terminals one after other. One will be the earth line and make no difference. One will be the feed thru the sw to the earth line -and appears to be encountering too much resistance - either in the sw, or the circuit after the sw. The feed wire earthed, HOPEFULLY will cause your pumps to stop. In which case you just need to determine whether it is the wire after sw or the sw is the problem. First thing - confirm you can stop the pumps by providing a decent earth to the correct plug terminal.
Alan
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83 SC, 82 930 (track) - Stock except for RarlyL8 race headers, RarlyL8 Zork, K27-7006, 22/28 T bars, 007 Fuel head, short 3&4 gears, NGK AFR, Greddy EBC (on the slippery slope), Wevo engine mounts, ERP rear camber adjust and mono balls, Tarret front monoball camber adjust, Elgin cams, 38mm ported heads, 964 IC. 380rwhp @ 0.8bar Apart from above, bone stock:-)
Old 03-19-2018, 12:30 PM
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Quick question:

**EDIT** I found a 108 and it didn't make a difference...

Anyone know the difference between these two Relays:

1. 911-615-108-01 - RED
2. 911-615-109-01 - BLACK

I just noticed that I have 109's on the Front Relays and the Engine Relay is a 108... I do not have another 108 to try - - so, this could be my problem as I've not been able to switch this out properly...
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Last edited by mooney265; 03-19-2018 at 12:57 PM..
Old 03-19-2018, 12:52 PM
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This describes the difference...

Red or Black Relay?
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Old 03-19-2018, 01:02 PM
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My car is currently running on a 109-01 in the rear. Makes no difference. I have black, red and brown ones. They are all configured the same. 85/86 is the energising circuit for the solenoid/relay. 30 is the high load +12V - there is always a live feed to the relay at 30. 87/87a is the high load switching on/off output. In the case of the FPs - 10+A
In the rear relay case it is slightly different. The airplate sw is the 85/86 energising low load (1-2A max) circuit. The o/boost circuit is the 'high' load output circuit of rear relay - but in this case it is only supplying low load energising power (85/86) to the FP front relays. Some cars seem to need the yellow rear relay to run - escapes me why - but several threads on it. Mine runs on any of the regular relays - as yours apparently does too.
Test the earth to the airplate sw plug. That should be definitive as to the problem.
Alan
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Old 03-19-2018, 02:17 PM
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When I put all back in it's place and remove the rear relay and run Ohms from the Rear Relay 85-pin to Chasis Ground, I get 27.3K Ohms. And, when I push down on the Meter Plate, it breaks the circuit... Sorry, but I'm not too sure what I'm supposed to make of the Ohms reading?
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Old 03-19-2018, 03:16 PM
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Old 03-19-2018, 03:18 PM
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That is the resistance of your solenoid circuit.
Pull the air plate plug. Key on. Pumps should be running. Take a wire well earthed and place other end on the PLUG terminals - either or. One of them should cause the pumps to stop. If that is the case - you have found the cause and we can direct you on how to fix it. basically tracking the bad earth wire - as Brian mentioned earlier.
Alan
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83 SC, 82 930 (track) - Stock except for RarlyL8 race headers, RarlyL8 Zork, K27-7006, 22/28 T bars, 007 Fuel head, short 3&4 gears, NGK AFR, Greddy EBC (on the slippery slope), Wevo engine mounts, ERP rear camber adjust and mono balls, Tarret front monoball camber adjust, Elgin cams, 38mm ported heads, 964 IC. 380rwhp @ 0.8bar Apart from above, bone stock:-)
Old 03-19-2018, 03:43 PM
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Ok, Here's what I've done:

1. All back as it should be
2. Turn Key On - Pumps Start
3. Remove Air Flow Plug - Pumps Continue
4. Jumper Left Side of Plug [This is the side I've determined goes directly to the #85] Direct to Ground - Pumps Continue to Run.
5. Jumper Right Side of Plug [This is the side I've determined already goes directly to ground] - And, of course, pumps still run...

I'm beginning to think this is working as it should and there is another problem?? Shannon
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Old 03-19-2018, 04:05 PM
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Also, what I've done:

1. Removed Air Flow Plug and ran Ohms
2. Left side of Plug goes directly 0-Ohms to #85 Socket
3. Right side of Plug goes directly 0-Ohms to Ground

Also, with plug removed:
1. Left side of Plug has no contact with Ground.
2. Right side of plug has no contact with #85 Socket

Also did the following:
1. All back as it should be
2. Removed Rear Relay and put alligator clip on #85-Pin [up tight to relay] and gave enough room to still plug in relay.
3. Put other end of alligator clip directly to Ground/Chassis.
4. Turned on Key - All pumps still run...

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Old 03-19-2018, 04:10 PM
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Nope - not supposed to run like that. problem may be further back up the line to relay.
The schematic is just a simplification of how it works. the actual wiring is Relay 85 - T14 - airplate sw - earth. A bad contact anywhere there will have same effect. my wiring diag is a bit fuzzy - but I think it is telling me pin #8 in T14. If you have a bad contact on that circuit in the 14 pin connector - same result. Pull the 14 pin plug on the box by the relay. The pins are numbered. Give them all a clean and the sockets too - I would use something like electro kleen or brake kleen and a pipe cleaner thing in the sockets. Splay the pins fractionally.
Or you can check by checking ohms between relay socket 85 and the contact on the plate plug. One will give you OL (no circuit) one should tell you how good that contact is between relay/T14/plug.
Alan
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83 SC, 82 930 (track) - Stock except for RarlyL8 race headers, RarlyL8 Zork, K27-7006, 22/28 T bars, 007 Fuel head, short 3&4 gears, NGK AFR, Greddy EBC (on the slippery slope), Wevo engine mounts, ERP rear camber adjust and mono balls, Tarret front monoball camber adjust, Elgin cams, 38mm ported heads, 964 IC. 380rwhp @ 0.8bar Apart from above, bone stock:-)
Old 03-19-2018, 04:21 PM
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Well, you have just done the other bits I would suggest. You have run an earth direct off 85. That should stop the pumps. You have checked circuit between plug/T14 /85, and zero ohms. I presume you mean that there is a complete circuit (as opposed to no circuit).
Alan
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83 SC, 82 930 (track) - Stock except for RarlyL8 race headers, RarlyL8 Zork, K27-7006, 22/28 T bars, 007 Fuel head, short 3&4 gears, NGK AFR, Greddy EBC (on the slippery slope), Wevo engine mounts, ERP rear camber adjust and mono balls, Tarret front monoball camber adjust, Elgin cams, 38mm ported heads, 964 IC. 380rwhp @ 0.8bar Apart from above, bone stock:-)
Old 03-19-2018, 04:46 PM
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Quote:
Originally Posted by Alan L View Post
Well, you have just done the other bits I would suggest. You have run an earth direct off 85. That should stop the pumps. You have checked circuit between plug/T14 /85, and zero ohms. I presume you mean that there is a complete circuit (as opposed to no circuit).
Alan
Yes, complete circuit... All's I know is that it all worked correctly for past 9-yrs of ownership; and suddenly [this weekend] it stopped working correctly...

The funny thing is, when the OB Plug is pulled, the pumps stop. This tells me that the Rear Relay is doing something... But, when I force a Ground onto #85 [with the relay plugged in], the pumps still run...

I'm gonna need a break... Alan: thank you for pushing me on this; but I'm at a loss for now... Shannon
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Old 03-19-2018, 04:54 PM
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As you can see from the schematic - the o/boost sw is the second leg of the relay circuit to the FPs. So breaking that circuit will stop the pumps.
I will ponder some more - maybe check some stuff on my car.
But this is a weird circuit even when working - because it is back to front in some aspect at the rear relay. I still can't completely rationalise the schematic in terms of the relay positions. There has been a few threads on this. may hunt some up.
Alan

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83 SC, 82 930 (track) - Stock except for RarlyL8 race headers, RarlyL8 Zork, K27-7006, 22/28 T bars, 007 Fuel head, short 3&4 gears, NGK AFR, Greddy EBC (on the slippery slope), Wevo engine mounts, ERP rear camber adjust and mono balls, Tarret front monoball camber adjust, Elgin cams, 38mm ported heads, 964 IC. 380rwhp @ 0.8bar Apart from above, bone stock:-)
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