dat240zg Posted March 24, 2012 Share Posted March 24, 2012 Well, this started several months ago when the Z started cutting out intermitantly and got to the point where it was undrivable. I started digging in to the wiring harness (potential for disaster: high) and found a whole nest full of screwups by the supposed "pro" that I initially paid to get the car going. Wires that were twisted/taped together for a connection, some butt connectors and a few soldered joints. And to add to that, there was extra wire out the wazoo. Wheelman encouraged me to dive in to it (go ahead jump!!!) so I got to pulling the entire harness from the car. BTW, I have no wiring experience beyond installing my own sound systems, so this was a big step. I figured that I could share the info that I gathered. If you're going to tackle this, you'll need (at least) the following websites: http://shbox.com/1/harness.htm and http://www.thirdgen.org/techboard/ltx-lsx/176800-lt1-wiring-dummies.html. I also decided that I needed to learn to solder well instead of just using butt connectors, researched that, bought a good solder gun and practiced on some scrap wire that I had. One cool/simple/cheap thing that I came up with was a way to build a rig to do my soldering in. I bought a set of aligator clips at Wal-Mart, cut the wires and inserted them, clip up, in my vice about 3 inches apart. Tightened the vice and, voila, a perfet way to hold my wires secure while I soldered them. Total cost: $1.38. I started by removing the harness and began tagging each wire and connector (I just used small pieces of masking tape to label each wire). Take your time on this and make sure that you're clearly labeling each one. Better to label well than to try to remember later. If you're just going to repair your harness, I wouldn't de-pin the ECU connectors. I wanted the harness to fit like it belonged in the Z, so I went ahead and labeled each wire at the ecu end (what it went to and which pin it went to - really important!!). To depin the ECU connector, open the clam shell covers on the back of the connector and then remove the colored cap on the front side (just takes a small flathead screwdriver and a gentle touch). Then, to depin the connector, lift the white retaining plastic piece with the flat head and gently push the pin out the back side of the connector. Again - don't do this unless you've really labled the pin number for each wire! Next step is to seperate all of the wires as much as possible. The LT1 harness (maybe others too?) is weird in that it uses common power and ground wires throughout - and the placement of these clumps of common power and ground wires doesn't make much sense. Make certain that you mark each wire where it enters each common power and each common ground. After seperating all of the wires, I found that it really boiled down to needing a common power on both the driver and passenger sides as well as one up nearer to the ECU. Same thing with the common grounds. After taking time to really get to know the harness and where things belong, I started by taking one connector at a time, plugging it in and measuring the amount of extra that I had at the ECU end. Then, depending on if the wire had been poorly connected or damaged, I either fixed the problems or shortened the wire as needed. To save your self a lot of frustration and time, make sure that you have all of your supplies before you start: Solder gun, solder, plenty of differnt sizes of wire heat shrink, a small torch (for the heat shrink), a good pair of wire strippers, wire cutters, scissors, electrical tape, masking tape and a fine point sharpee (for labeling wires). The old adage of measure twice, cut once really applies here. You don't want to get your wires too short (where you have to stretch them to fit - not bueno). Once you do cut the wire, make sure that you slide a piece of heat shrink to cover the solder or butt connector before you connect them back. Don't ask me how many times I forgot to do this. Plan on taking the harness in and out 3 or 4 times before you finish. Also, if you're a beginner like me, plan on the job taking a solid 4 days. Once you've repaired/trimmed the wires, begin building up the harness on the Z. Especially on the LT1, make certain that your grounds are done well. Also, as you're going through the harness, look for damaged connections - I found one on the optispark connector that was damaged and needed repair. When all your wires are done and triple checked, plug everything back in but don't wrap it back up. Test it first. I was fortunate that it started first time. Which was then quickly followed by me running around in the front yard yelling like a crazy man. The neighbors are used to it now. After that, I re-wrapped the harness all pretty and called it finished! One nice side benefit of this job was that I'm not nearly as freaked out by wiring - rather, the harness makes sense now and I believe that I'll be able to diagnose things better as a result of knowing it better. Here is the wire listing for the LT1 that I used from the thirdgen website (I didn't come up with it - they have a resident LT1 expert): A is RED PCM connector. B is BLACK PCM connector. C is GREY/CLEAR PCM connector. D is BLUE PCM connector. Pinout Color Where it goes: A2 blk/wht PCM Ground A3 blk Injector #1 Control A4 lt blu/blk Injector #4 Control A5 yel/blk Injector #6 Control A6 red/blk Injector #7 Control A7 dk grn/wht Fuel Pump Relay Control A9 gry EGR Vacuum Control Signal Solenoid Valve Ctrl A10 dk blu Secondary Cooling Fan Relay Control A11 dk grn Cooling Fan Relay Control A12 tan/blk Electronic Brake & Traction Control Module A13 wht TACH Output A14 brn Air Pump Relay Control A15 dk blu Performance Mode Indicator Lamp Control A18 tan/wht PCM Ground A19 lt grn/blk Injector #2 Control A20 blk/wht Injector #5 Control A21 pnk/blk Injector #3 Control A22 dk blu/wht Injector #8 Control A23 orn/blk Electronic Brake & Traction Control Module A25 dk blu Fuel Enable Signal(Theft Detterant System) A31 ppl VSS Ground A32 yel VSS Signal B1 dk grn/wht A/C Request Signal B2 red/blk Low Resolution Signal B3 pnk/blk Distributor Reference Low Signal B5 wht Ignition Control B6 blk A/C Evaporative Temperature Sensor B6 blk A/C Refrigerant Pressure Sensor B6 blk TPS Ground B6 blk Trans Fluid Temperature Sensor B7 lt grn 1-2 Shift Solenoid Control B8 dk grn/wht VSS Output B12 yel/blk 2-3 Shift Solenoid Control B13 gry Skip Shift Solenoid Control B13 wht Control Solenoid B14 red Distributor Ignition Feed B15 orn PCM Battery B16 blk MAP Ground B19 yel MAF Sensor Signal B20 ppl/wht OR lt blu/blk High Resolution Signal B21 dk grn A/C Clutch Status B28 gry 5v TPS Reference B28 gry A/C Refrigerant Pressure Sensor B29 gry MAP 5v Reference B30 pnk PCM Ignition Feed B31 orn PCM Battery C1 lt blu/wht IAC Coil C2 lt blu/blk IAC Coil C5 lt grn/blk IAC Coil C6 lt grn/wht IAC Coil C7 tan rt o2 Sensor h02s LOW C8 ppl rt o2 Sensor ho2s HIGH C11 lt blu Electronic Brake & Traction Control Module C13 lt blu Performance Mode Switch Signal C14 lt blu/blk Brake Signal C15 orn/blk Park Nuetral Position Sensor(4L60E ONLY) C16 red/blk Pressure Control Solenoid C19 tan/wht lt o2 Sensor ho2s LOW C20 ppl/wht lt o2 Sensor ho2s HIGH C21 tan IAT Sensor Signal C22 dk blu TPS Sensor Signal C23 lt grn Map Sensor Signal C25 yel ECT Sensor Signal C28 pnk Trans Fluid Temperature Sensor C29 dk blu Trans Fluid Temperature Sensor C30 red Trans Fluid Temperature Sensor C32 blk/wht PCM Ground D1 tan/wht PCM Ground D2 lt blu/wht Pressure Control Solenoid D6 brn Torque Convertor Clutch Solenoid D6 lt grn Reverse Inhibit Solenoid Control D8 dk grn/wht A/C Clutch Relay Control D9 brn/wht Malfunction Indicator Lamp D10 dk grn/wht EVAP Canister Purge Solenoid Valve Control D11 tan/blk Torque Convertor Clutch Solenoid D12 red A/C Refrigerant Pressure Signal D12 red/blk A/C Refrigerant Pressure Sensor D15 wht Skip Shift Lamp Control(T56/T5 ONLY) D20 wht/blk Output Field Service Enable. D22 dk blu Knock Sensor Signal D24 dk blu A/C Evaporative Temperature Sensor D24 dk blu A/C Evaporative Temperature Sensor Signal D28 yel/blk Trans Fluid Temperature Sensor D30 pnk PCM Ignition Feed D30 tan Serial Data Hope this may help someone else get brave/crazy. Have a great one! Bryan Dat240zg Quote Link to comment Share on other sites More sharing options...
GOTHALOSISM Posted March 24, 2012 Share Posted March 24, 2012 Is this for the MAF of speed density systems? Quote Link to comment Share on other sites More sharing options...
dat240zg Posted March 24, 2012 Author Share Posted March 24, 2012 MAF. Quote Link to comment Share on other sites More sharing options...
GOTHALOSISM Posted March 24, 2012 Share Posted March 24, 2012 kool, now i just need to get a harness for the maf system. I already have the ecu and the maf sensor, I'm running speed density with the eprom chip now. Quote Link to comment Share on other sites More sharing options...
dat240zg Posted March 24, 2012 Author Share Posted March 24, 2012 Let me know if I can help you with info. Bryan Quote Link to comment Share on other sites More sharing options...
rsicard Posted March 27, 2012 Share Posted March 27, 2012 A speed density EFI system DOES NOT USE a MAF sensor! Quote Link to comment Share on other sites More sharing options...
dat240zg Posted March 28, 2012 Author Share Posted March 28, 2012 "Is this for the MAF of speed density systems?" I may be wrong, but I think he meant to type MAF or Speed density. Quote Link to comment Share on other sites More sharing options...
GOTHALOSISM Posted March 30, 2012 Share Posted March 30, 2012 Yes I have the MAF sensor but and the ecu to go with it, I also have a speed density ecu with standalone harness. When I got the harness it came with the ecu. I wanted the maf system but the price was out of my reach at the time. All I need now is the harness that will work with a 94+ ecu. Quote Link to comment Share on other sites More sharing options...
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