Big Blue's Transformation

[Gary Lewis]

Probably was the DG/O as the whole interior came out of a 1996 crew cab.

Thanks, Bill. I guess we'll see if grounding the return will work. Don't see how to do it otherwise.

[85lebaront2]

Thanks, Bill. I guess we'll see if grounding the return will work. Don't see how to do it otherwise.

Here is where my speed control wiring connects to the main dash harness.

[Gary Lewis]

Here is where my speed control wiring connects to the main dash harness.

Thanks, Bill. That's interesting as you have 4 connections - ground plus the three from the horn pad. The Bullnose has but two plus ground.

But, as I look at the wiring from the '96 EVTM, below, it occurs to me that what they've done is provide a ground to the system via the speed control. The horn circuit absolutely has to have ground in order to pull the horn relay in, and it has to flow as shown by my red lines and through the horn switch. So the speed control must provide that ground. Right?

If that is the case then my plan will work. In fact, I really don't need to ground the DG/O wire and just let the speed control provide the ground.

I'll go test that theory in a few minutes - after finishing the 2nd cup of joe.

[ratdude747]

Thanks, Bill. That's interesting as you have 4 connections - ground plus the three from the horn pad. The Bullnose has but two plus ground.

But, as I look at the wiring from the '96 EVTM, below, it occurs to me that what they've done is provide a ground to the system via the speed control. The horn circuit absolutely has to have ground in order to pull the horn relay in, and it has to flow as shown by my red lines and through the horn switch. So the speed control must provide that ground. Right?

If that is the case then my plan will work. In fact, I really don't need to ground the DG/O wire and just let the speed control provide the ground.

I'll go test that theory in a few minutes - after finishing the 2nd cup of joe.

What ford did (on the bullnose at least) is use the horn relay's power connection as a 12V supply for the cruise "on" switch by using the relay side of the horn switch as said reference. Idea being that nobody is going to honk the horn and turn on cruise at the same time, and the input circuitry of the cruise control module is so low current that that the relay coil appears as a dead short (the electrical adage of how all resistors have effectively no voltage drop if the current is negligible).

The upside of this design? Saves one slip ring contact (only need two plus the column ground) while not having to reengineer the cruise control module to use 100% NPN (pulled-up) inputs. The downside? Besides being confusing for people not familiar with the circuit, if you pop the cigarette lighter and horn fuse, you also lose the ability to activate cruise control since that relay is also sourced from said fuse (drove me batty for the better part of an afternoon).

I'll give Ford an "A" for creativity on this one.

[Gary Lewis]

What ford did (on the bullnose at least) is use the horn relay's power connection as a 12V supply for the cruise "on" switch by using the relay side of the horn switch as said reference. Idea being that nobody is going to honk the horn and turn on cruise at the same time, and the input circuitry of the cruise control module is so low current that that the relay coil appears as a dead short (the electrical adage of how all resistors have effectively no voltage drop if the current is negligible).

The upside of this design? Saves one slip ring contact (only need two plus the column ground) while not having to reengineer the cruise control module to use 100% NPN (pulled-up) inputs. The downside? Besides being confusing for people not familiar with the circuit, if you pop the cigarette lighter and horn fuse, you also lose the ability to activate cruise control since that relay is also sourced from said fuse (drove me batty for the better part of an afternoon).

I'll give Ford an "A" for creativity on this one.

Yes, it was creative. And it wasn't just for the On switch, but also for all the other control inputs, like Off, Set, Resume, etc.

They liked the design so well that they continued to use it at least until '96 after apparently introducing it in '80 as the part numbers start with E0. Same resistor values for all the switches, so same voltages sent to the speed control to decode - even though there were several iterations in the speed control unit itself.

But it isn't easy to see that they used the same design as they redrew the schematic for the later years. Here's the Bullnose schematic on the left and the '96 schematic on the right. The only difference is the addition of one more clock spring for the "return", as discussed. (That, and forgetting to show how power is supplied as they mistakenly show it applied to the box around the schematic. )

 

[Gary Lewis]

Thanks, Bill. That's interesting as you have 4 connections - ground plus the three from the horn pad. The Bullnose has but two plus ground.

But, as I look at the wiring from the '96 EVTM, below, it occurs to me that what they've done is provide a ground to the system via the speed control. The horn circuit absolutely has to have ground in order to pull the horn relay in, and it has to flow as shown by my red lines and through the horn switch. So the speed control must provide that ground. Right?

If that is the case then my plan will work. In fact, I really don't need to ground the DG/O wire and just let the speed control provide the ground.

I'll go test that theory in a few minutes - after finishing the 2nd cup of joe.

There's no connection from Pin 6 of the later speed control, which is Common Return, and Pin 10 which is Ground.

[85lebaront2]

Yes, it was creative. And it wasn't just for the On switch, but also for all the other control inputs, like Off, Set, Resume, etc.

They liked the design so well that they continued to use it at least until '96 after apparently introducing it in '80 as the part numbers start with E0. Same resistor values for all the switches, so same voltages sent to the speed control to decode - even though there were several iterations in the speed control unit itself.

But it isn't easy to see that they used the same design as they redrew the schematic for the later years. Here's the Bullnose schematic on the left and the '96 schematic on the right. The only difference is the addition of one more clock spring for the "return", as discussed. (That, and forgetting to show how power is supplied as they mistakenly show it applied to the box around the schematic. )

One item, a 1996 > 8500 lb truck does not have a clock spring, it uses brushes like the 80s models. You are going to make me get the 1995 F450 column down and get pictures of it just so you have proof.

[Gary Lewis]

One item, a 1996 > 8500 lb truck does not have a clock spring, it uses brushes like the 80s models. You are going to make me get the 1995 F450 column down and get pictures of it just so you have proof.

I'm missing something. How does looking at an '95 F450 column prove that a '96 > 8500 lb truck does not have a clock spring? You do have me curious.

As for what I did today, I took 2 steps forward and 1 backward, but that should still count as progress. Right?

I got 8 more wires run between the ECU and the PDB. That leaves me 4 more wires to run that I know of - 2 for VSS and 2 for the misfire sensor. And I've actually run the misfire sensor wires from the PDB end to the ECU but haven't connected them there. That's because I need to label them and I've run out of label tubing, and the order won't be in until Friday.

As for the 1 step back - I discovered that the labels on 3 of the ignition wires are wrong. As it happens those wires are to be shielded, and the shielding came in today. So I pulled the pins out of the ECU connector and worked the shielding over the wires and down to the place near the PDB where the original shielding was cut and soldered it to the drain wire with the original shielding. I also put shielding over the 2 misfire wires and connected it to the original shielding's drain wire as well. So now I'm just waiting on the label tubing to come in so I can finish up the wiring. However, I could start testing.

On another front I have a date for the bucket seats to be rebuilt - Juneish. But that gives me time to look up the codes, contact SMS to get samples, and get everything nailed down before taking them to the guy - in Kansas.

 

[85lebaront2]

I'm missing something. How does looking at an '95 F450 column prove that a '96 > 8500 lb truck does not have a clock spring? You do have me curious.

As for what I did today, I took 2 steps forward and 1 backward, but that should still count as progress. Right?

I got 8 more wires run between the ECU and the PDB. That leaves me 4 more wires to run that I know of - 2 for VSS and 2 for the misfire sensor. And I've actually run the misfire sensor wires from the PDB end to the ECU but haven't connected them there. That's because I need to label them and I've run out of label tubing, and the order won't be in until Friday.

As for the 1 step back - I discovered that the labels on 3 of the ignition wires are wrong. As it happens those wires are to be shielded, and the shielding came in today. So I pulled the pins out of the ECU connector and worked the shielding over the wires and down to the place near the PDB where the original shielding was cut and soldered it to the drain wire with the original shielding. I also put shielding over the 2 misfire wires and connected it to the original shielding's drain wire as well. So now I'm just waiting on the label tubing to come in so I can finish up the wiring. However, I could start testing.

On another front I have a date for the bucket seats to be rebuilt - Juneish. But that gives me time to look up the codes, contact SMS to get samples, and get everything nailed down before taking them to the guy - in Kansas.

 

Clock springs are needed for the air bag detonator as the brushes may break contact in a collision. Trucks over 8500 GVWR were not required to have air bags, therefore no need for a clockspring.

[Gary Lewis]

Clock springs are needed for the air bag detonator as the brushes may break contact in a collision. Trucks over 8500 GVWR were not required to have air bags, therefore no need for a clockspring.

Now that makes sense!