wiring questions 5.3 into 99 hoe

[tommypvt]

Did a little more work last night on the harness. Ran into the first major differences in wiring between the 03 and the 99. I focused on the Backup light wiring and the starter relay wiring.

The backup light wiring was somewhat interesting. The connector for the back up light wiring (under the brake booster) is also shared with the fuel pump power. The BU/Fuel12v+connector is tied to the the underhood fuse box by the grey fuel pump wire as well as to the c100(d3) with the lt green backup light wire. I believe the backup lights run into the cabin to shut off the auto dimming rearview mirror when backing up.

The difference with the 03 is that the backup circuit also runs to the underhood fuse box to power a backup alarm branch and then continues on to the BCM of the 03 when it outputs from the BCM it changes to light green to power the backup lights. So this changes the color of the wiring a bit.

The backup lights circuit runs from the IP fuse block Fuse 16 to the PNP switch on the tranny. This is a pink wire located at C7 of the C100 connector. This pink wire has to be connected to the PNP connector pin F which is the backup 12v+ voltage . What makes this all fun is that that power wire is light green on the 03 harness. And in my case extra fun because the connectors were also cut off the PNP switch.

So pink from C7 on C100 to the light green back up power wire Pin F on the PNP. The lt green PNP wire runs to the under hood fuse box in the 03. When I depinned or cut out the 03 fuse box wiring I labeled all of the wires with the fuses that they were running to. So this made it easy to figure out that it was the backup wire.

The return from the PNP switch is a Gray wire. It runs to the fuse box as well to feed that branch backup circuit. So I had it labeled Trailer because the fuse on the 03 is trailer/BU. I extended the gray wire and ran it to the light green on the backup connector.

This should be it for the backup wiring. I will type up the starter relay wiring when I get my notes in front of me. The big differences between the 03 is the passlock or whatever that is not in the 99 and getting the right wires connected to the PNP switch.

I will make some diagrams when I have some time.

 

[tommypvt]

So worked on the harness most of the day and got it pretty much sorted.

Ran power to the injectors and Ho2 sensors etc. Tied everything into the ecm-1 fuse. There was a pink wire with a ton of splices from i believe the 99 injector harness.

I tested out the trans plug pink power terminal E and ran that to a2 of the c100 bulkhead plug.

Ran a new pin from ecm c2-38 to C2 on the c100 bulkhead plug for the fuel gauge.

Spliced in C3 on the C100 to the alternator wiring for the charge indicator lamp.

I am running the three wire coolant switch so had to wire that in.

Hooked up the obd2 from b7 on the bulkhead c100 to the 03 c100 pin H

I ended a bunch of wires that i didnt need in the harness. All the 4wd wiring etc.

Hooked up the speedo signal and the tach feed. Not sure i have the right speedo signal there are two wires on the c100 03 plug that are speedo wires so if the one i have connected doesnt work i will go to the other. Tach should be fine. Speedo and tach are both feed through the c100 bulkhead connector.

I extended the chmsl/stoplamp wire so that it is close to the other cruise wiring on the c100. I will cut the plug that went to the old cruise module and run wires from it to the harness. I would like to put a plug in there. So i can pull the harness but i am going to wait to hook up the cruise.

And probably did a bunch of other things I cant remember. The harness should be ready to go in tomorrow. Hopefully no huge issues. Still need to wire in the trans range plugs and run splices over to the passenger side bulkhead for the electronic prdnl

 

[tommypvt]

Got the harness in today. But still had to finish a bunch of stuff.

Started by extending the wiring that is running from the passenger side bulkhead. This is just the wiring for the prdnl display it gets run down to the pnp and trans range plug on the side of the trans.

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There is a connector under the passenger side lower dash i believe c200. I thought c200 was the bulkhead but i now think it is this connector.

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I pulled it down and tested out the wires. The only reason was because there is two yellows in the connector that run different circuits on the trans. So i figured out what was what and went on to the range switch. I ran the wiring down the firewall.

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I connected the prdnl wiring to were it had to go on the trans. It is getting spliced in with the engine harness wiring at the switch. It would be cleaner to try to get into the harness and splice out a pigtail but i didnt know where to place it and there is a yellow wire that the ecu doesnt use and the prdnl does so you would have to add a wire. No big deal but i was trying to keep the harness together.

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I wish the plugs would have come off the trans it would have made it alot easier than soldering under the car. There were a couple issues with the engine harness to range switches . The harness has 2 black and white wires at the range switches. My harness was chopped so no plugs. One is a ground the other goes the range A wire. So I had to test out the range circuit to the ecu pin and then wire the other black and white to the ground. It was even more confusing because both the 03 and 99 diagrams have the ground as black at the plug. But it is black and white and on the 03 ground schematic it is black and white.

I just have to finish a couple more wires and it should be good enough to run. I need to cut the wires for the cruise and the TCC line out of the plug going to the old cruise control.

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I am going to dbw so I dont need this plug it would be cool to run a male weatherpak connector here and just wire it in that way.

I still have to figure out the AC wiring and connect a couple wires running from the passenger side (mil,heater power, oil pressure and coolant temp) but it is pretty much done. Hopefully it will work ok. I will have the engine in this week.

 

[GMRedline]

Wow. I thought it was supposed to be easy?

Thanks for sharing.

 

[tommypvt]

Wow. I thought it was supposed to be easy?

Thanks for sharing.

It would be easier to go to the 411 pcm and keep the old harness i think. Then add your injector wiring etc. Also easy to just get it running with a standalone harness.

Doing it this way is not terrible if you can read wiring diagrams but not easy by a long shot but totally doable. Much more so now that I have done one.

This job has confimed I really need to invest in some weatherpak stuff. I think i am going to cut all the connectors out of the donor i have and keep them for future use.

 

[tommypvt]

Got everything connected and she fired right up. Some limited problems. The oil pressure gauge is pegged. I am guessing the three wire sender can't work without power I am going to swap over to an older single wire sender and I imagine that will fix it. Also the RPMS aren't reading on the dash they read over the OBD2 though. so I may have to add a resistor ala lt1swap.

Have one code p1125 for the DBW pedal. Not sure what the issue is but ordered a new harness to go between the TAC and the pedal. Hopefully that will fix it. I had to splice a new connector in because on my donor the guy had cut the DBW harness out and the in car half was missing. So I may have screwed something up connecting the wires. I imagine that is what is wrong because I didn't change anything on the wiring except for that.

 

[tommypvt]

New dbw harness arrived and the pedal related code disappeared. So as i figured it was all in my splice job. I must have wired something wrong. But of of the whole job not bad. Have a pending p1637 generator L terminal low voltage. Not sure what thats about but will try to sort that. Otherwise good to go hopefully have her back on the road next week.

 

[MikeH]

How did you wiring up your A/C system? and how did you get your tach to work?

 

[tommypvt]

never got my stock tach to work. Not sure what is up. I tried the resister or whatever that didn't work ether. No ac yet but I am in the process of that now.

Ended up swapping in a nv3500 instead of the 4l60e. I couldn't not get the 4l60 to work when I reinstalled it. I imagine it was something I did but Dunno.

 

[MikeH]

My Tach didnt work at first either, There was a white wire connected to the ignition module on the L31 by the coil that goes to the stock tach. I had to wire that to the ecu I believe it was RED 10. I connected that white wire from the cab to RED 10 and now I have a Tach again. I also had to modify the tach signal in HP tuners for it to read correctly.