Lock Up Converter Vacuum Switch FAIL???

[MadOgre]

Well let me know what you find in your adventures

 

[chengny]

I need to figure out where the power comes from that goes to the vacuum switch now. I checked all my fuses, and they are all good. This thing is really starting to piss me off, Just last night I had full power to one of the wires of the vac switch, all of a sudden I ain't got nothing.

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I would like some info on what and which wires go where too. I had a 6.2 diesel and I need to wire it up the gasoline way. I assume it is the same but I don't know as I never gave it a second thought when I was pulling out the diesel cause I had the th400 then.

It's wired the same as above.

 

[MadOgre]

Thanks. I only have 2 conections at the TCC and im pretty sure I do not have an ECM?

 

[chengny]

Sorry, I checked your model year only and missed the diesel application.

I didn't think that diesels used a vacuum switch. Are the two wires light blue & light green?

Here are the TCC wiring diagrams for 1983 & 1986 (non -Cal) with diesel engines:

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[MadOgre]

Ya I think I have 2 wires blue and green or brown and green. looks like they go from the transmission up into the firewall and not sure after that.

But I pulled the diesel and need to make it work for the gas set up now.?

ill have to take a good look tomorrow.

 

[VAL]

I only have two wires going to the vacuum switch, both are light blue, one has a black stripe on it. I have 3 wires going down to the tranny.

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[chengny]

For VAL:

Here is the wiring diagram for the only system that agrees with what you are telling me.

It has 2 wires (LT BLU & LT BLU /BLK) that connect to a vacuum switch and it has three wires (YEL, LT BLU & LT GRN) that run down and connect to a 4 prong plug.

The wires coming out of the other side of the plug are connected to the TCC solenoid/switch group in the transmission.

The hot wire is brown coming out of the fuse block (plugged in to the ACC group), but changes to light blue after it comes out of the brake switch.

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[Boone83K10]

VAL, you and I have the same setup. I am missing the EGR bleed solenoid (where it turns to yellow wire). PO stuck a wire across the EGR plug after the engine swap. I am going to cut out the plug and solder it together with new wire.

That is the correct diagram that chengny put up. You obviously need a new trans plug.

as for the ACDelco TCC switch... my 83 plug will not hook up to that. it is round.

 

[MadOgre]

Sorry, I checked your model year only and missed the diesel application.

I didn't think that diesels used a vacuum switch. Are the two wires light blue & light green?

Here are the TCC wiring diagrams for 1983 & 1986 (non -Cal) with diesel engines:

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K so I got 3 wires coming out of the firewall and that splits into 2 to the tranny and 2 to a plug just like the diagrams.

the plug does not quite fit the TCC switch.

Is it just a matter of wiring the TCC switch to the 2 wires at the plug ? I don't have the throttle switch that the plug originally plugged into.

 

[MadOgre]

Also I have a 700r4 out of a 90 suburban. will I have any issues there? with the wiring?

I see on here that they can be wired differently from year to year at the tranny

 

[chengny]

Mad-O; I'm am kind of losing track of your exact situation.

The vehicle in question is an 84 pick up, 1/2 ton with 4WD - true?

As for the power plant, you currently have a stock 350 coupled to a 700R4 transmission (RPO = MD8) - right?

The truck's wiring harness/controls are stock, and everything was originally set up for a TH400 transmission driven by a 6.2 liter diesel motor?

And, your objective is to get power (from the stock wiring/control components) down to the 700R4 and energize the internal TCC solenoid - correct?

If I am getting something wrong as described above, let me know. We'll see if we can somehow reconcile the two different set ups (i.e. the gas power plant you have now vs. the wiring and controls that came with the diesel plant).

BTW - I hope I have not given the impression that I am an expert on this subject. Because trust me, I'm not.

Everything I know is only what I have picked up since stumbling across this thread... what - like 3 days ago.

Also, something to be aware of; all the "advice" I post on TCC's comes entirely from what I find while reading schematics and service manuals. I have never even seen a TCC solenoid or a low vacuum switch in my life. All my trucks have been very basic - and they all came from the factory without O2 sensors, catalytic converters, EST/ESC.

As the saying goes - "When it comes to advice, consider the source".

 

[VAL]

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So I pulled out the harnes that goes down to the tranny, through the engine bay area. I have another connector(pinkish red) that was just hanging on the firewall, not connected to anything.WTF!

 

[VAL]

For VAL:

Here is the wiring diagram for the only system that agrees with what you are telling me.

It has 2 wires (LT BLU & LT BLU /BLK) that connect to a vacuum switch and it has three wires (YEL, LT BLU & LT GRN) that run down and connect to a 4 prong plug.

The wires coming out of the other side of the plug are connected to the TCC solenoid/switch group in the transmission.

The hot wire is brown coming out of the fuse block (plugged in to the ACC group), but changes to light blue after it comes out of the brake switch.

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I think I have a gremlin, I traced the wires going through the firewall into th cab, found the brown power wire on the block, checked it with the meter and it gave me 12volts, 30 seconds later I check it again, and theres no power.

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[VAL]

VAL, you and I have the same setup. I am missing the EGR bleed solenoid (where it turns to yellow wire). PO stuck a wire across the EGR plug after the engine swap. I am going to cut out the plug and solder it together with new wire.

That is the correct diagram that chengny put up. You obviously need a new trans plug.

as for the ACDelco TCC switch... my 83 plug will not hook up to that. it is round.

Do you have th350 or the 700r4?

 

[Boone83K10]

700r4 as it came from GM