I've got a 1996 F350 XL 4x4 ZF5 Crew. I picked up a cruise control horn pad from the junkyard this week, installed it, and no cruise. So I searched the archives here for common problems and made sure my fuses are good, brake lights work, etc. Also, Brake on/off and clutch sensors are working properly. I think that the problem would lie in the BPA sensor, or lack thereof. My master cylinder does not have this sensor. I looked at Ford online parts catalog and it lists different master cylinder p/n's for cruise and non-cruise trucks. One of the threads I read through mentioned jumpering a connector with a paper clip. I would assume this would be the connector that goes to the BPA sensor. Can someone help me out with this. A photo showing a master cylinder with BPA sensor hooked up or at least a photo/diagram showing which connector goes to it would be nice. In the area of the M/C I've got three connectors that are not hooked up. One is at the top of the firewall, coming off the harness to wiper motor, so I think it's for an underhood lamp. There are two that have 4 wires each and have a grey plastic plug to cover/protect the contacts. Is either one of these the BPA connector?

 

The BPA has 2 terminals in the connector. The paperclip idea will work temporarily because the switch is normally closed. I would'nt keep it on there tho. The CC may not release when you step on the brake.

 

So where is the connector for the BPA, or which part of the harness does it split off from? I'll pull the air cleaner tomorrow so I can see down in that area better but a little guidance on where to look would be helpful. Do I have to replace my M/C with the correct one for CC trucks for this to work properly? Doesn't the Brake On/Off switch kill the cruise?

 

The connector must be close to the end of the MAster cylinder if you even have one?? I'll get a picture of mine today.

You may need to have the PCM reflashed because our diesels are "fly by wire". You might need to replace the steering column too. The BPA is redundant to the BOO.

Here's what the manual says:
Components
The vehicle speed control subsystem consists of the following components:

Steering column and controls
Brake on/off (BOO) switch
Clutch pedal position (CPP) switch
Horn relay assembly
Vehicle speed sensor assembly
Brake pressure applied (BPA) switch
Wiring harness
Powertrain control module (PCM)
The PCM inputs that are used for speed control consist of the following:

Vehicle speed sensor signal — A sine wave with frequency proportional to speed (variable reluctance sensor).
Vehicle speed sensor signal ground — The signal provides the ground reference for the vehicle speed sensor signal.
Speed control driver command switch signal — This is a variable DC voltage determined by driver selection of steering wheel control switches, fed through slip ring and brush contacts.
Speed control driver command switch signal return — This signal provides the ground reference for the command switch signal.
Brake on/off switch signal — Provides the PCM with an on/off signal based on brake pedal position.
Brake pressure applied switch signal — Provides the PCM with an additional redundant on/off signal based on brake pedal position.
Clutch pedal position switch signal — Provides the PCM with an on/off signal based on clutch pedal position.

This is the electrical schematic.
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There are a few things that you need to pull this off. First of all, the "clock spring" harness - if you look at the harness on your truck , you'll see that there are only two wires coming off of the three wire connector on your clockspring(one cavity is empty). They travel about 6 inches down the right side of the column and plug in to another connector. You need to make the connection between the clock spring and that connector midway of the steering column. I would suggest going back to the junkyard and getting that small harness off of the one that has cruise. If you're feeling bold you can use the diagram Cuda_jim posted and run your own wire.
The other thing is, use a relay to bypass the BPA. What I do is connect the two wires from the BPA circuit to the normally closed contacts on the relay (30 & 87a) and splice in to the brake light switch wire (to the side that's hot with the brakes applied) and run a feed from that to the relay coil terminal (85) and then a ground wire to the other coil terminal (86). The reason for that setup is that the PCM checks to see if the BPP (brake pedal position) and the BPA are in agreement (ie brake lights on, BPA open brake lights off, BPA closed) and if they aren't it disables the cruise. Of course if you really wanted to be safe you could just get the right master cylinder with the BPA.
The good news is that all 7.3l PCM's have cruise enabled, so you don't have to do a reflash.

 

BPP = BOO. Oops...my bad!

 

p.s. the wires for the BPA switch are black with a purple stripe and pink with an orange stripe.

 

spike, sounds like you've done this b4. I have not and was hesitant to give out what little knowlege I have.

Is the BPA harness on all trucks?

Most bone yards won't disassemble the parts off a steering column, especially Fords trucks. You may get stuck buying the whole thing, at least that's been my experience.

 

Thanks for the help guys. I think I've got enough info to get this going now.

 

Yeah, I've done it a few times. Makes people real happy cuz it's cheap! And as far as the BPA harness, yeah it's there. Kind of amazing how they just leave a wire out here and a couple of switches there so that you don't have cruise.

 

Adding cc to mine was as simple as replacing the horn pad and using the paperclip. It worked fine. However, I think the paperclip might not always carry enough current as that circuit is all tied into the speed sensor circuit and can make the truck do weird things. I was having problems with the flashing od light occasionally (another long story). I put the old horn pad back on and removed the paperclip and no more problems. If i continue to have no problems, I will get the switch for the master cylinder and do it right.

 

I got it working yesterday. I found the BPA connector and closed the circuit with a crimp-on spade connector. The prongs were spaced perfectly to fit into the terminals of the connector. It probably has much better current carrying capacity than a paperclip anyway, and it's a nice tight fit so it shouldn't rattle loose. I also don't have to worry about TC lockup and OD issues since I've got the 5sp. I don't like it as a permanent solution, but at least I know it works now.

 

Guess I should've read a little closer, didn't realize you had the 5sp. That makes the relay a bit of overkill since all it does is fool the pcm into thinking you have a BPA switch. Sounds like you got it going ok anyways!