in the middle of wiring my 69

[bonnieclyde100]

i am in the middle of wiring my 69 chevy truck with a 700r4 in it. i have a few questions that i cant seem to find answers for .first what wires do i have to have hooked to the data port to work with tunerpro or a code reader? second im tryng to hook up my drac so i can hook it to my pcm and run cruise control run a speedometer but all wiring scematics i look at dont match my wires and i dont know if having a 700r4 changes how i hook it up.i will send pic of my drac. third the pcm wants a brake signal from RWAL module but i dont have antiloc brakes nor do i have a brake switch like in the 90s trucks. any help would be appreciated

[Six_Shooter]

Go by pin position when it comes to connecting the DRAC. There seems to be several colour options for the wires over the years, pin out remained the same though.

As far as the brake input goes, you can use your current brake switch and use a relay to mimic how the newer switches work for cruise.

[bonnieclyde100]

this diagram is the closest i have to my drac it shows only 8 pins and mine has nine in one section and four in another of course not all of them are used. and do you use the relay to send a ground to the cruise ? is that how a factory switch works?

Go by pin position when it comes to connecting the DRAC. There seems to be several colour options for the wires over the years, pin out remained the same though.

As far as the brake input goes, you can use your current brake switch and use a relay to mimic how the newer switches work for cruise.

[bonnieclyde100]

i figured it out there are two pinouts for the speedometer and only one is used. is the diagram below better?

[bonnieclyde100]

will i need this what ever this is in the left picture that the brake signal wires are going in and out of to hook up my brake signal to the pcm? also here is where my pcm will be mounted in my truck glove compartment. any ideas on how to mount it? how did you mount it pitures would be great?

[lionelhutz]

I try to use the original mounting bracket. It's best to have the PCM mounted so the case is electrically insulated from the body.

[bonnieclyde100]

i dont have one but i figured that and i am just mounting it in the glove box where it no metal. thanks for the info

I try to use the original mounting bracket. It's best to have the PCM mounted so the case is electrically insulated from the body.

[bonnieclyde100]

i figured out how the factory switch works constant ignition power until brakes are pressed then no power and i know how to make a relay do that. thanks for the info

Go by pin position when it comes to connecting the DRAC. There seems to be several colour options for the wires over the years, pin out remained the same though.

As far as the brake input goes, you can use your current brake switch and use a relay to mimic how the newer switches work for cruise.

[Six_Shooter]

The first pinout you posted is for a Digital Ratio adapter. It's basically the same as a DRAC, functionally, but has a different pinout as you see. The second pinout is for a DRAC and should match up to the DRAC you have perfectly.

Yes, that is correct about the TCC power.

Use existing brake switch to trigger the relay to open when the brakes are pressed. I use ignition to pin 87A and then 30 out to the TCC. I wired my boss' '64 Suburban to work this way (SBC, 700R4, with a '7747).

As suggested, isolate the ECM from the chassis, this is VERY important. I went through two '7747s in another friend's '67 pick up before figuring this out. I usually make plastic brackets if I can't find a factory one that will work. I'll post some pictures later this week, if I get a chance, Exams are killing me this week.

[lionelhutz]

Use existing brake switch to trigger the relay to open when the breaks are pressed. I use ignition to pin 87A and then 30 out to the TCC. I wired my boss' '64 Suburban to work this way (SBC, 700R4, with a '7747).

Doesn't that mean the relay is always energized and adds another drain onto the battery?

Should just find a new switch with the correct contacts, try an early 90's S10 or full size pickup.

[Six_Shooter]

No, not at all. The relay will only activate when the brake pedal is pressed. When the ignition turns off, there is no power passing through the contacts of the relay to the TCC.

The brake wire connects to 85 or 86 and ground on the other opposite coil pin. I.E if the brake wire is connected to 85, then ground is connected to 86.

In some vehicles, like these '60s trucks, the brake switch is mounted very differently than late model vehicles, and so it's often easier to use a relay.

I'm not saying that swapping to a different switch isn't a good idea, it just can end up being more work than it's worth, when a relay will work just as well.

[lionelhutz]

OK, just make sure to use a relay with a normally closed contact. Not all of them do.

[Six_Shooter]

Ummm, that would be the only way it would work...

[lionelhutz]

Not the only way. You can hook the coil between an ignition source and the output of the brake switch and then the relay will be energized and closed when the key is on and the brakes are not pressed.

[Six_Shooter]

Not the only way. You can hook the coil between an ignition source and the output of the brake switch and then the relay will be energized and closed when the key is on and the brakes are not pressed.

That would be the most convoluted way to make it work, and might not be reliable. You may also find that the brake lights may have a dim glow to them. I think I've seen exactly two (Bosch style) relays in my long time (25+ years) working with automotive electronics that didn't have a N.C. contact, and they were both from Hella Fog/driving light kits, that had two N.O. contacts instead. So the likelihood that the OP would get a relay without a N.C. is slim to none.