Big Blue's Transformation

[ratdude747]

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. )

Look again. Only the Cruise "on" switch is referenced to the horn relay (+12V referenced). The other switches are ground referenced. The only reason I can think they'd want "On" to be a +12V reference is to ensure that a short to ground (with varying amounts of resistance) or off switch bounce couldn't cause the system to somehow activate and set unintentionally without having to add another slip ring brush. Thinking about it that way, it makes sense. Short to +12, the system activates but cannot set. Short to ground, the system never activates (and if it's a dead short, the system is forced off). Only intermediate ground referenced resistances allow for the cruise to set/resume...

[Gary Lewis]

Look again. Only the Cruise "on" switch is referenced to the horn relay (+12V referenced). The other switches are ground referenced. The only reason I can think they'd want "On" to be a +12V reference is to ensure that a short to ground (with varying amounts of resistance) or off switch bounce couldn't cause the system to somehow activate and set unintentionally without having to add another slip ring brush. Thinking about it that way, it makes sense. Short to +12, the system activates but cannot set. Short to ground, the system never activates (and if it's a dead short, the system is forced off). Only intermediate ground referenced resistances allow for the cruise to set/resume...

Larry - I agree with what you are saying. But I don't understand the "Look again." I don't think I said anything contrary to what you said. And what you said applies to both schematics.

What am I missing?

[ratdude747]

Larry - I agree with what you are saying. But I don't understand the "Look again." I don't think I said anything contrary to what you said. And what you said applies to both schematics.

What am I missing?

If I'm reading your post correctly, it was stated that all the switches are referenced to the horn solenoid... not just the On switch. Which is incorrect. All other switches (to include the actual horn switch) are ground referenced.

[Gary Lewis]

If I'm reading your post correctly, it was stated that all the switches are referenced to the horn solenoid... not just the On switch. Which is incorrect. All other switches (to include the actual horn switch) are ground referenced.

I don't see that in what I said. But in any event, you are right.

[Gary Lewis]

I don't see that in what I said. But in any event, you are right.

Got quite a bit of testing done today, and it all tested correctly. In fact, as shown below, I got all but three connections tested, and they are:

 

• The two wires for the misfire sensor which haven't been connected as I'm waiting on the labels to come in and want to slip the labels over the wire before soldering the extension on.

 

• The single PTO wire, which just comes out of the ECU connector and doesn't go anywhere so it didn't seem reasonable to say I'd tested it. In fact, I don't know if my ECU has that feature built in, but I thought I'd try it anyway. However, I'm not sure what it even does, so...

 

Also I ordered some 10A 100V rectifier diodes today, one of which will go on the A/C clutch circuit to protect the ECU. I measured the clutch current draw at 3.9A, so these diodes should be able to handle the back EMF and protect the ECU.

 

As I think about it, there is a bit more testing I can do before installing the whole thing. For instance I can add power to the PDB and see that all the relays work as they should. I tested the ECU power and fuel pump relays today, but I can easily check the horn, backup light, and fog light relays. And if anything needs to be changed, now is the time.

 

Hopefully the labels will come in early tomorrow and I can button up the wiring and then tidy things up with convolute and tape. Maybe it'll be time for some pics then.

 

[1986F150Six]

Got quite a bit of testing done today, and it all tested correctly. In fact, as shown below, I got all but three connections tested, and they are:

 

• The two wires for the misfire sensor which haven't been connected as I'm waiting on the labels to come in and want to slip the labels over the wire before soldering the extension on.

 

• The single PTO wire, which just comes out of the ECU connector and doesn't go anywhere so it didn't seem reasonable to say I'd tested it. In fact, I don't know if my ECU has that feature built in, but I thought I'd try it anyway. However, I'm not sure what it even does, so...

 

Also I ordered some 10A 100V rectifier diodes today, one of which will go on the A/C clutch circuit to protect the ECU. I measured the clutch current draw at 3.9A, so these diodes should be able to handle the back EMF and protect the ECU.

 

As I think about it, there is a bit more testing I can do before installing the whole thing. For instance I can add power to the PDB and see that all the relays work as they should. I tested the ECU power and fuel pump relays today, but I can easily check the horn, backup light, and fog light relays. And if anything needs to be changed, now is the time.

 

Hopefully the labels will come in early tomorrow and I can button up the wiring and then tidy things up with convolute and tape. Maybe it'll be time for some pics then.

 

Like I have said before, your work is impressive!

[Gary Lewis]

Like I have said before, your work is impressive!

Thanks, David.

But I'm expecting there to be problems when I install things. I'm planning to test things w/o the ECU installed to protect it, but I can still see if the horn works, the A/C clutch comes in, etc. Should be interesting.

[Bruce moose4x4]

Thanks, David.

But I'm expecting there to be problems when I install things. I'm planning to test things w/o the ECU installed to protect it, but I can still see if the horn works, the A/C clutch comes in, etc. Should be interesting.

Gary, sometimes the PTO is used to idle up the motor speed and such, For example an ambulance while on scene would help keep the alternator running faster to keep all the lights going. Looked for an upfitters manual for your truck but just found this. I know all those years ambulances I worked on had a fast idle but not sure if they were by the computer or they added a solenoid to the throttle cable. Been pre 1991 when I was working on them and firetrucks.

https://www.ebay.com/itm/402350539806

Not sure if it would have the information in it you need. The body builders book are easy to find for the later years.

Just so you'll know I'm glad your doing the wiring and not me.

[Gary Lewis]

Gary, sometimes the PTO is used to idle up the motor speed and such, For example an ambulance while on scene would help keep the alternator running faster to keep all the lights going. Looked for an upfitters manual for your truck but just found this. I know all those years ambulances I worked on had a fast idle but not sure if they were by the computer or they added a solenoid to the throttle cable. Been pre 1991 when I was working on them and firetrucks.

https://www.ebay.com/itm/402350539806

Not sure if it would have the information in it you need. The body builders book are easy to find for the later years.

Just so you'll know I'm glad your doing the wiring and not me.

Thanks, Bruce. I'm hoping that this feature will do just exactly that, up the idle speed. That would be handy when using lots of juice, like when winching.

Here's what I see in the '96 EVTM:

• 5.0L: Pin 4 Circuit 323 LB/Y Customer Use. Shows in the schematic, shows on the ECU connector pinout diagram, and on the ECU connector's pinout table.

• 5.8L under 8500 GVWR: Pin 4 Circuit 323 LB/Y Customer Use. Shows on the ECU connector pinout diagram and on the ECU connector's pinout table, but not on the schematic.

• 5.8L over 8500 GVWR: Not shown anywhere.

• 7.5L California: Pin 4 Circuit 323 LB/Y Power Take Off Circuit. Shows on the ECU connector's pinout table and shows as on the ECU Connector pinout diagram, but doesn't show on the schematic.

But, I think my ECU started life in a 5.8L, although it has been tweaked to fit my application, and I don't know if it was above or below 8500 GVWR. So does it have that function in it? If not, maybe I need to start with a 5.0L ECU to get that feature? I wonder if this is a question for Core Tuning?

As for the body builder's book, thanks but we have that one on the site. You can see it in the Manuals & Literature spreadsheet, but I don't think it has info on that feature.

[85lebaront2]

Thanks, Bruce. I'm hoping that this feature will do just exactly that, up the idle speed. That would be handy when using lots of juice, like when winching.

Here's what I see in the '96 EVTM:

• 5.0L: Pin 4 Circuit 323 LB/Y Customer Use. Shows in the schematic, shows on the ECU connector pinout diagram, and on the ECU connector's pinout table.

• 5.8L under 8500 GVWR: Pin 4 Circuit 323 LB/Y Customer Use. Shows on the ECU connector pinout diagram and on the ECU connector's pinout table, but not on the schematic.

• 5.8L over 8500 GVWR: Not shown anywhere.

• 7.5L California: Pin 4 Circuit 323 LB/Y Power Take Off Circuit. Shows on the ECU connector's pinout table and shows as on the ECU Connector pinout diagram, but doesn't show on the schematic.

But, I think my ECU started life in a 5.8L, although it has been tweaked to fit my application, and I don't know if it was above or below 8500 GVWR. So does it have that function in it? If not, maybe I need to start with a 5.0L ECU to get that feature? I wonder if this is a question for Core Tuning?

As for the body builder's book, thanks but we have that one on the site. You can see it in the Manuals & Literature spreadsheet, but I don't think it has info on that feature.

If it is the one I sent you it did start as a 5.8L version. They are fairly common and the automatic was either a C6 or E4OD. The E4OD one is what I am using on Darth. The actual 460 MAF/SEFI/E4OD EEC is an FEZ 0 1 2 or 3 tag number (I have one). Hardware code is ML1-441 which IDs them as V8, E4OD MAF and were also used on 5.0L applications.

I have a list of all the numbers, catch codes etc. If you would like.