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Help! Disconnected wires.


74OH2

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Hello everyone! I need help. I can't figure out what this wiring harness ends connect to. I've been trying to trace it back by comparing to the wiring diagram but I'm having a hard time tracing them...it's a 1974 BMW 2002

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Edited by 74OH2
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1 hour ago, torquewrench80 said:

This probably isn't what you want to hear, but I always look for something disconnected that is in reach of those wires, since they will only stretch just so far. Then you'll have something else to work with, not just the wires, to make sure that of where they go.

I'm open to all suggestions...so this is what I have come up with. The single wire (brown wire black stripe) with the black cap (furthest to the left in the picture) reaches the water temp sensor that is located under the intake manifold. The 2nd single wire (black wire brown stripe) in the center of the picture does not having anything close by to plug into. The 3rd 2 wire (green wire white stripe and a solid green) furthest to the right in the picture reaches the starter solenoid. And the 4th wire in the picture where you can see my hand holding it is a single wire (solid green) and I can not find anything that's this wire would connect to.

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Edited by 74OH2
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One of those wires (and I can't remember which) is for the anti-dieseling valve that was fitted to your original Solex carb.  If you connect a voltmeter to ground and to each wire in turn, the one that's hot only with the ign on is the anti-dieseling valve lead.  Unless you fit one to your Weber, it's not needed, but do tape it firmly out of the way so it doesn't ground and cause sparking and/or a fire as it's hot whenever you're running the car.  

 

I suspect the others are the remains of an at least partially removed emission control system.  '74s had a rather elaborate system; the dead giveaway is that all those unused wires are part of a single, separate wiring harness that unplugs from the main harness at a single point.

 

mike

'69 Nevada sunroof-Wolfgang-bought new
'73 Sahara sunroof-Ludwig-since '78
'91 Brillantrot 318is sunroof-Georg Friederich 
Fiat Topolini (Benito & Luigi), Renault 4CVs (Anatole, Lucky Pierre, Brigette) & Kermit, the Bugeye Sprite

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All the green/white wires come from the #12 fuse (8A), and provide +12 volts when the ignition is on to: 1) speed relay, 2) EGR relay, 3) Choke relay, 4) Electric choke, 5) Idle cutoff solenoid, 6) Air temp switch (which powers the themostatic valve on the Solex carb). You only need connections to the electric choke (if used) and the cut-off solenoid (if your Weber has one).

 

The brown/black wire connects the EGR relay to the coolant SWITCH located under the intake manifold (near the support bracket for the starter). This relay controls the Red electro-valve and EGR valve.

 

The brown/green wire connects to your oil pressure switch (next to distributor)

 

The brown/white wire connects to you coolant temperature SENDER located on top of the coolant branch.

 

The green/black wire connects the speed relay to the White electro-valve, which controls the Dash Pot (not used w/ Weber)

 

The green/red wire connects the EGR relay to the Red electro-valve, which controls the 1st stage of the EGR valve.

 

The green/yellow wire connects the choke and EGR relays to the Black electro-valve, which controls the vacuum advance/retard on the distributor.

 

Did you find any other wire colors that are not mentioned above? 

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8 hours ago, John76 said:

All the green/white wires come from the #12 fuse (8A), and provide +12 volts when the ignition is on to: 1) speed relay, 2) EGR relay, 3) Choke relay, 4) Electric choke, 5) Idle cutoff solenoid, 6) Air temp switch (which powers the themostatic valve on the Solex carb). You only need connections to the electric choke (if used) and the cut-off solenoid (if your Weber has one).

 

The brown/black wire connects the EGR relay to the coolant SWITCH located under the intake manifold (near the support bracket for the starter). This relay controls the Red electro-valve and EGR valve.

 

The brown/green wire connects to your oil pressure switch (next to distributor)

 

The brown/white wire connects to you coolant temperature SENDER located on top of the coolant branch.

 

The green/black wire connects the speed relay to the White electro-valve, which controls the Dash Pot (not used w/ Weber)

 

The green/red wire connects the EGR relay to the Red electro-valve, which controls the 1st stage of the EGR valve.

 

The green/yellow wire connects the choke and EGR relays to the Black electro-valve, which controls the vacuum advance/retard on the distributor.

 

Did you find any other wire colors that are not mentioned above? 

Great info! Thank you for sharing your knowledge! You covered all the wires I came across. 

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10 hours ago, Healey3000 said:

Hi,

 

Not what you asked but since it's a '74, why not strip out all the emissions components?  It really cleans up the engine compartment and in your car's case, they are partially disconnected anyway.

I would love to strip it all out, the problem is that I don't really have a good guide to tell me which components and wires i need to strip out. I need picture description to walk me though this....with all due respect to the desmogging posted, I really have not been able to find a post with step by step instructions. If a post does exist, please send me the link. Thanks. 

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Mark92131

 

Smog removal

 

1. Buy a used early exhaust manifold, (no emission ports), or a Tii manifold or a non-thermal reactor manifold and plug the emission ports, or headers, or the IE Shorty Header.

2. Pull the Thermal reactor (smog manifold) off, 8 nuts, plus the bracket to the passenger-side engine mount, disconnect the hoses to the EGR filter (rear) and Check valve (front), toss in neighbors pool, (actually someone may need it because they crack).

3. Remove your alternator and battery, you will need clearance for the EGR filter and smog pump.

4. Unbolt the EGR filter from the intake manifold (2 bolts), remove the hoses (one is connected to the intake manifold, the other to the divertor), and vacuum lines from the EGR Valve.  Slide the EGR Valve and filter into the space vacated by the alternator to remove.

5. Buy the EGR blocking plate on the FAQ store, to plug the hole in the intake manifold (or use one of those rubber expanding plugs)

6. Remove the Dashpot for the Solex carb from the intake manifold, if it is still there, if you have a Weber carb, it is probably gone

7. Remove the T1 Temperature switch between 3 & 4 on the intake manifold (keep, they are expensive)

8. Remove the Diverter Valve (between the EGR Valve and the Pump), 3 hoses and bracket

9. Remove the Air pump, belt, and mounting brackets, (under the battery tray), it takes some wiggling to get it past the sway bar.

10. Replace the Alternator and battery (leave battery disconnected for now)

11. Remove all the smog components attached to the firewall (3 electro-magnetic valves (red, white, black), 2 relays, (speed & choke), the Control valve (round with 3 vacuum lines), the EGR Relay (looks like an aluminum cigarette pack).

12. Plug the 3 open ports on the intake manifold from unplugging the smog stuff.

13. Run a single vacuum line from the carb port above the port on the intake manifold, (passenger side of the carb) to the advance port on the distributor, plug the retard port on the distributor, (underneath).

14. If you have an electric choke or idle jet shut-off circuit, it might be powered off of the emission wiring harness (blue sheath wire bundle connecting all the firewall smog components), you'll need to power those things separately to remove the smog harness (run wires off the + side of the coil)

15. To remove the smog harness, trace the blue sheath wire bundle to the fuse box, remove the screw for the fuse box and pull it up, there should be two wires connected, disconnect both of them.  The push-on connection at fuse #12 should be used to connect to the + side of the coil.  If you have a coil with an internal resistor (blue, aftermarket) run a straight wire from fuse #12 to the + side of the coil, if you have the original black coil or red, you need to harvest the resistor wire from the smog harness (still connected to the coil), or use the older external style resistor that mounts on the firewall.  Either way, trace the smog wiring harness back to the coil and remove it completely.  If you need to harvest the resistor wire on the + side of the coil connection, peel back the blue sheath to expose the clear resistor wire and remove it and then splice it into your new wire running back to the fuse box.  The only thing connected to the coil will be the wires from the distributor to the - side of the coil and your new wire from the fuse box #12 to the + side of the coil.  If you have Pertronix, those wires will also be present.

16. Reconnect the battery and start the car

17, Set the dwell and timing

18. Reset the carb to best idle using the idle jet screw, set the idle speed and enjoy.

 

Good luck,

 

 

M.

     DISCLAIMER 

I now disagree with some of the timing advice I have given in the past.  I misinterpreted the distributor curves in the Blue Book. 

I've switched from using ported-vacuum to manifold, with better results. 

I apologize for spreading misinformation.  

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