Tarheel Blue Posted February 1 Share Posted February 1 I’m in transition from an ‘85 300 I6 w/ NP435 (with vacuum speed control) to a ‘95 4.9L w/ 4R70W (with electronic speed control) While switching out the pedal assembly it became apparent that now is the most convenient time to do any wiring changes as it relates to the speed control. Months ago I acquired the necessary servo/ amplifier, cable and about 6” of harness. I’ve spent the last couple of days reading all that I can on previous threads from Gary, Jeff and others. Very helpful but somewhat confusing as most all pertain to manual transmissions or dealer installed kits. Soooo . . . . I have a couple of questions. In the ‘96 EVTM - circuit 848, “speed control switch return” Do I simply run that wire to ground as Gary suggests in the Big Blue thread? - circuit 307, “brake pressure input” My master cylinder does not have provisions for this “fire hazard” switch. Do I cap this wire off? In essence creating the “open when system has pressure” state necessary to allow use of the controls? - circuit 306, “clutch pedal position switch”. I will no longer have this switch so I’m assuming that I need to provide a jumper, out of a couple female spade terminals and wire, at the connector (as the EVTM diagram implies) - circuit 679, “vehicular speed input”. I would very much like to retain the use of my stock VSS that is part of my speedometer cable (just under the master cylinder) It has two wires, the DG/W would be the signal and the BK should be ground. Can I just run the BK wire over to the firewall with a ring terminal and a self tapper? Or does it need to be tied into the harness somewhere? Link to comment Share on other sites More sharing options...
ArdWrknTrk Posted February 1 Share Posted February 1 Kurt, I need to look at the '96 EVTM. There's a lot going on here,.. But if you're looking for a ground there's one right below the wiper motor. That stud should be tied to your intake or block. ALL grounds in the truck are tied together. If the schematic shows ground it doesn't matter. Link to comment Share on other sites More sharing options...
Gary Lewis Posted February 1 Share Posted February 1 Kurt, I need to look at the '96 EVTM. There's a lot going on here,.. But if you're looking for a ground there's one right below the wiper motor. That stud should be tied to your intake or block. ALL grounds in the truck are tied together. If the schematic shows ground it doesn't matter. Jim - We have the '96 EVTM, but here's a link to the speed control bit: https://www.garysgaragemahal.com/speed-control1.html I'll see if I can rethink what I did and answer the specific questions. But I can say that what I did worked and worked well. And the stock Bullnose VSS works perfectly with the later speed control. Link to comment Share on other sites More sharing options...
ArdWrknTrk Posted February 1 Share Posted February 1 Jim - We have the '96 EVTM, but here's a link to the speed control bit: https://www.garysgaragemahal.com/speed-control1.html I'll see if I can rethink what I did and answer the specific questions. But I can say that what I did worked and worked well. And the stock Bullnose VSS works perfectly with the later speed control. I know it's here, but I don't know it inside out Appreciate the link though Link to comment Share on other sites More sharing options...
Tarheel Blue Posted February 1 Author Share Posted February 1 I know it's here, but I don't know it inside out Appreciate the link though Thanks for looking into this for me. After posting, I’m wondering if perhaps I asked questions in a confusing way. It might have been better for me to list the circuit numbers from the ‘85 EVTM, as those are the existing wires in the original harness that I’m trying to marry up to a ‘95 device. If a comparison chart would help, let me know and I’ll pull one together. Link to comment Share on other sites More sharing options...
ArdWrknTrk Posted February 1 Share Posted February 1 Thanks for looking into this for me. After posting, I’m wondering if perhaps I asked questions in a confusing way. It might have been better for me to list the circuit numbers from the ‘85 EVTM, as those are the existing wires in the original harness that I’m trying to marry up to a ‘95 device. If a comparison chart would help, let me know and I’ll pull one together. Identifying the circuits you need would definitely be a big help. Hopefully my phone will stop freaking out and I'll find some time tonight to work on it. Link to comment Share on other sites More sharing options...
Gary Lewis Posted February 1 Share Posted February 1 Identifying the circuits you need would definitely be a big help. Hopefully my phone will stop freaking out and I'll find some time tonight to work on it. I have my schematics in CAD on the shop computer, so can check out what I did, but not until tomorrow afternoon. Link to comment Share on other sites More sharing options...
Tarheel Blue Posted February 1 Author Share Posted February 1 Identifying the circuits you need would definitely be a big help. Hopefully my phone will stop freaking out and I'll find some time tonight to work on it. OK, lets see if this helps at all. First off is the factory installed vacuum speed control. There are three major connectors between the amplifier that is under the dash and the servo itself in the engine bay. The larger of the two at the amplifier has 6 wires and is noted as C714 and the connector at the servo also has 6 wires and is noted as C753. All 6 of these wires seem to simply be a jumper to send info from the amplifier to the servo. The smaller of the two amplifier connectors also has 6 wires and is noted as C717. Pinouts as follows; Circuit Wire Color Purpose 57 BK Ground 57A BK VSS Ground 150 DG/W VSS Signal 295 W/P 12+ (15a fuse) HOT IN RUN 151 LB/BK H Steering Pad 511 LG Clutch Switch/ Stop Lamp HOT AT ALL TIMES The '95 electronic speed control. This device has one connector with 7 wires; Circuit Wire Color Purpose 679 GY/BK VSS Signal 306 T/LB Brake Light Switch 151 LB/BK Common Signal 848 DG/O Common Return 298 P/O 12+ 307 BK/Y Brake Pressure 901 R/LB Ground Link to comment Share on other sites More sharing options...
mat in tn Posted February 2 Share Posted February 2 OK, lets see if this helps at all. First off is the factory installed vacuum speed control. There are three major connectors between the amplifier that is under the dash and the servo itself in the engine bay. The larger of the two at the amplifier has 6 wires and is noted as C714 and the connector at the servo also has 6 wires and is noted as C753. All 6 of these wires seem to simply be a jumper to send info from the amplifier to the servo. The smaller of the two amplifier connectors also has 6 wires and is noted as C717. Pinouts as follows; Circuit Wire Color Purpose 57 BK Ground 57A BK VSS Ground 150 DG/W VSS Signal 295 W/P 12+ (15a fuse) HOT IN RUN 151 LB/BK H Steering Pad 511 LG Clutch Switch/ Stop Lamp HOT AT ALL TIMES The '95 electronic speed control. This device has one connector with 7 wires; Circuit Wire Color Purpose 679 GY/BK VSS Signal 306 T/LB Brake Light Switch 151 LB/BK Common Signal 848 DG/O Common Return 298 P/O 12+ 307 BK/Y Brake Pressure 901 R/LB Ground are you installing ford ecu/tcm or an aftermarket tcm for the 4r70w? how does this relate to the speed control? Link to comment Share on other sites More sharing options...
Tarheel Blue Posted February 2 Author Share Posted February 2 are you installing ford ecu/tcm or an aftermarket tcm for the 4r70w? how does this relate to the speed control? TCM will be by Bauman, a Quick 4, shouldn’t have any communication? Also, TBI will be the Holley Sniper 2bbl, again, shouldn’t have any communications? Link to comment Share on other sites More sharing options...
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