electical - need to ground charge relay

superhl

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I am trying to get my heater fan to work. My 1992 isuzu pickup conversion to vw 1.9l diesel has a white/blue wire that needs to be connected the VW alternator which upon charging then grounds the charge relay which engages the heater relay allowing the heater fan to run. Anyone know where I connect blue/wht wire to the alternator.
Here is the schematic for the Isuzu. http://repairguide.autozone.com/znet...52800627d9.gif
 

CasaEd

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Tried looking at your schematic, but not showing up for me. Also is your engine TDi, and if so which one ?
 

superhl

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Engine: 2002 new beetle 1.9l diesel
Truck: 1992 Isuzu LS space cab (pup)
Had a guy by the name of Paul to respond on the Isuzu site. Here is what he stated..
"In the P'up the charge relay is used to allow the heater blower to run only when the engine is running.

This done by driving the charge relay coil from the 'L' lead on the alternator. One terminal of the relay coil is grounded via a black wire and the other terminal is connected to the 'L' lead of the alternator via a White/Green wire. The relay coil is designed so that the relay will close at around 9 volts, providing battery power to the blower.

This works OK in the Pup. And this can be implemented with your VW conversion by finding the 'L' lead coming from the VW alternator and connecting the White/Green wire to it.

If you cannot find the VW 'L' lead wire, you could connect the White/Green wire to any ignition switched voltage source and then the heater blower will come on any time the ignition is on and the blower switch is on (the engine need not be running)."
Question: Where is the "L" lead on the VW alternator??

http://repairguide.autozone.com/zne...F:US:EN:AZ:NL:1000000:GEN:ppjmid43737-8-11065
 
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CasaEd

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I don't think you can use the wire on the VW alternator. So if i'm understanding this

correctly, if you connect the white/green wire to earth so the heater blower will work ?
 

Alchemist

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I see two ways of doing this, that is electrical or mechanical.

The mechanical is to use the Isuzu alternator on the VW engine and leave the wiring as built by Isuzu.

The electrical is to make the Isuzu compatible with the VW alternator since the VW alternator doesn't have the connections that Isuzu uses.

The diagram you linked to doesn't show a White/Green wire, but it could be White/Violet or White/Blue on the diagram.

To reconfigure for the VW alternator you will need to do the following.

1. Remove charge and heater relays.

2. Remove fuse 8.

3. Disconnect White/Red wire from fuse 5 and connect it the VW alternator Pin 2 Blue
wire. In a VW, the Blue wire connects to the Instrument Cluster warning lamp.

4. Connect Blue/Red wire from junction of fuses7B and 8B to the Black/Yellow wire at the junction of fuses 7 and 8.

When this is done, fuse 5 will no longer supply power to the White/Red wire at the left side of the diagram for the 2.6L engine controls. If you need this in your conversion, it will have to be sourced from a different location such as fuse 7 Yellow wire.
 

Vince Waldon

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Another alternative might be a simple relay that supplies a ground connection to the Isuzu heater wiring when the coil of the relay is activated by a "power when the key is ON but not START" circuit, 75x for example.

I don't suspect it's super important that the heater run only when the alternator is charging.. my guess is it's more about not having the heater as a load when trying to start the car... which circuit 75x will accomplish.
 

Alchemist

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Good idea Vince, but the heater relay needs an active high to energize. Perhaps just using the accessory lead from the Isuzu ignition switch to supply the heater relay might work.

This also does not deal with the charge indicator lamp which supplies field current to start the alternator, hence the major rewire I suggested.

As always, there is more than one way to get there.
 

superhl

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I see two ways of doing this, that is electrical or mechanical.

The mechanical is to use the Isuzu alternator on the VW engine and leave the wiring as built by Isuzu.

The electrical is to make the Isuzu compatible with the VW alternator since the VW alternator doesn't have the connections that Isuzu uses.

The diagram you linked to doesn't show a White/Green wire, but it could be White/Violet or White/Blue on the diagram.

To reconfigure for the VW alternator you will need to do the following.

1. Remove charge and heater relays.

2. Remove fuse 8.

3. Disconnect White/Red wire from fuse 5 and connect it the VW alternator Pin 2 Blue
wire. In a VW, the Blue wire connects to the Instrument Cluster warning lamp.

4. Connect Blue/Red wire from junction of fuses7B and 8B to the Black/Yellow wire at the junction of fuses 7 and 8.

When this is done, fuse 5 will no longer supply power to the White/Red wire at the left side of the diagram for the 2.6L engine controls. If you need this in your conversion, it will have to be sourced from a different location such as fuse 7 Yellow wire.
Will this also help resolve my check engine light, alternator, and brake light from staying on continuously??
 

superhl

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Another alternative might be a simple relay that supplies a ground connection to the Isuzu heater wiring when the coil of the relay is activated by a "power when the key is ON but not START" circuit, 75x for example.

I don't suspect it's super important that the heater run only when the alternator is charging.. my guess is it's more about not having the heater as a load when trying to start the car... which circuit 75x will accomplish.
Vince,
What is 75x?
 

Alchemist

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Will this also help resolve my check engine light, alternator, and brake light from staying on continuously??
It should only correct the alternator light problem and make your heater work.

Do you have the codes for the engine light?

The brake light wiring is not on that diagram, so I can't be of much help there. It does seem unlikely to be related.

Not wishing to put words in his mouth, but Vince is using the VW terminology for accessory power, AKA 75X. This appears to be the Black/Yellow wire from the ignition switch.
 

Vince Waldon

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Yup, sorry, was not being very clear.

In the VW world "75x" is a current line that is active when the key is turned to "ON" but goes off when the key is turned to "START". Big loads like headlights and heater fans are powered via this line, so that they turn off when attempting to start the engine, thus saving power for the starter.

My suggestion was to find a similar line on your Izuzo chassis and use it to power a relay that gives you the ground you need to enable your heater.

There's no comparable signal wire on a factory VW alternator, so you're going to have to look elsewhere.

That said, if you're willing to disassemble your alternator, you could run a wire from the stator side of the diode bridge. Such a wire would go hot when the alternator starts charging... which could be used to drive a relay that provides ground.

Multiple ways to skin this cat. :)
 

superhl

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It should only correct the alternator light problem and make your heater work.

Do you have the codes for the engine light?

The brake light wiring is not on that diagram, so I can't be of much help there. It does seem unlikely to be related.

Not wishing to put words in his mouth, but Vince is using the VW terminology for accessory power, AKA 75X. This appears to be the Black/Yellow wire from the ignition switch.
Thanks! I don't have the codes. I have the OBD for the TDI side but the truck does not have an OBD on the Isuzu side. Could it be a ground? It more annoying than anything. The low fuel light is also on.
 
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superhl

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From the charge relay, I located the white/blue wire. What if from the 75x wire on the Isuzu, I connect the white/blue wire, would that engage the charge relay which would activate the heater relay?? I need to put something together in a drawing. I have to visually see what I am doing. I would prefer to stay with VW alternator if possible. I don't have much working room. I'm off for a couple of weeks and will have more time to get this resolved.
 

superhl

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I think this will do what you want. If you have any more questions, ask away.

Alchemist,
Here is correct schematics from the Mitchel website. Can you look at this and verify the wires that need to be re-routed. Thanks a bunch. I want to make sure I don't kill my fuel pump.



Is this correct?


From the Mitchell website:
 
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Alchemist

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After comparing the Auto Zone and Mitchell drawings, I have determined that they are the same, just organized differently.


Your diagram will work as drawn.


Since you are concerned about not fusing the line to the charge relay it could be modified to do this. Just take the Yellow wire from the charge lamp and connect it to the VW alternator Blue wire before Fuse 7. The top of Fuse 7 would then remain connected to the ignition switch, and the bottom of Fuse 7 would go to the Charge Relay.


When wired this way, the fuel pump will run when the key is on, even if the engine is not running. This wouldn't be a problem unless you had an accident where the fuel system was damaged and the pump continued running, pouring fuel out.
 

superhl

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I wired the yellow/white to Blue/White. Now when I turn on the ignition switch, I hear the charge relay come on. However, the fan still is not working. I need to test the fan switch for current. Not easily accessible. Will attempt this weekend. I can remove the charge relay fuse (5) and the fuel pump continues to receive current. So charge relay has no control over the fuel pump. The schematic above show a white wire that feeds the fuel relay. Correct?
 

Alchemist

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For reference purposes, and to avoid confusion, there is a convention used in wiring. The first colour is the basic one and the second is the stripe. Black/Red would be a black wire with a red stripe, while Red/Black would be a red wire with a black stripe.



I am assuming you connected the White/Yellow and White/Blue wires to supply the charge relay with switched 12V. This should activate the Heater relay and supply power to fuse 7B.


The blower motor Blue/Black wire is grounded through the resistor pack and speed selector switch. Grounding this wire will prove the motor works and point to the switch or resistor as the cause.


The fuel pump relay is operated by the White wire from the Charge Relay through fuse 6 and the White/Red wire on the diodes, or the Yellow wire which comes in on the left from some other source. Or is that fuse 5A? It is hard for me to make out the print on that part of the diagram. The other source may be what is keeping the fuel pump running.



 

superhl

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I connected the wht/yel wire to wht/blu wire and all is working. Thanks for the great help. However, I have another issue. I had a problem with the engine cranking 3-4 revolutions before starting. Matt sent me a loader to capture the config file. I competed and return the config to Matt. I received the fix and appeared to resolve the starting issue. However, now I can get "No response from controller". It worked perfectly before the tune fix. I tried the troubleshooting steps at the VAGCOM website. PIN 15 has 12.5V and PIn 4 and 7 are displaying 12V. I think 4 and 7 should be reading under 9V. Is it the tune or is something else wrong?? I did get it to work briefly today. I was about to do a back flip and it stopped working. Any suggestions?
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