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I am wiring up a 4age bigport into my son's car. What I need help on is what do I do with the old sr5 harnes that sits in the passenger side footwell. Second, I do have the harness for the engine, but only two plugs fit the ECU and one plug that supposedly goes to the junction block (how do I wire that in?). I have an mr2 harness to get that critical 14? pin plug for the ecu, the problem encountered is the engine harness has wires already going to the AFM. But that plug has wires going to the AFM also. Do I just splice into that? It's just that passenger juction block area has me all confused to no end. Finally, If I use the C block, what do I omit what do I keep. I am trying to get this car back to my son ASAP. Any help is greatly appreciated. I will post pics in the next day or two.

Any chance the SR5 was automatic with cruise control?

it's a 5 speed without cruise. Any way I tore into the dash and engine harness, removed all the tape and systematically traced every wire and labeled them. Then repinned all the wires into the correct slots. Just a couple more wires and I will be done. I used a multimeter to ensure all the wires had continuity. I had issues with the color coding of the MR2 harness vs. the Ae86 harness wchich is the last couple of wires. I will be installing it here shortly. On another note, those that are having issues sourcing a GTS diff for their conversion, I have an option for you. 79-92 mustangs carry a 8 inch rear that is the same lug pattern of the AE86 and is about 1 inch wider on each wheel (57 in.) Just measure , cut and weld in the AE86 mounts voila!! The choices of gearing for the 8 inch are numerous. Remember that the GT's had the LSD's in them if I am not mistaken. If anyone needs help, post a pic and I will see if I can help.

qn60e6 wrote:it's a 5 speed without cruise. Any way I tore into the dash and engine harness, removed all the tape and systematically traced every wire and labeled them. Then repinned all the wires into the correct slots. Just a couple more wires and I will be done. I used a multimeter to ensure all the wires had continuity. I had issues with the color coding of the MR2 harness vs. the Ae86 harness wchich is the last couple of wires. I will be installing it here shortly. On another note, those that are having issues sourcing a GTS diff for their conversion, I have an option for you. 79-92 mustangs carry a 8 inch rear that is the same lug pattern of the AE86 and is about 1 inch wider on each wheel (57 in.) Just measure , cut and weld in the AE86 mounts voila!! The choices of gearing for the 8 inch are numerous. Remember that the GT's had the LSD's in them if I am not mistaken. If anyone needs help, post a pic and I will see if I can help.

Right on there! Great info on the rear end as well

The main reason I was asking about it being a cruise control model is because SR5 AE86s w/ cruise control have the gauge cluster w/ the appropriate pinout for the speed sensor signal (VSS?) the 4AG ecu is looking for. SR5s w/o cruise don't have that pinout nor the provisioning on the back of the speedometer gauge.