Engine wiring question(s)
 

I am trying to start my LS engine and I do not seem to be able to get it to crank. I do have power to the engine as the throttle butterfly "twitches" when connected.
the engine is a 2013 4.8 with the factory uncut harness and factory underhood fuse box with the factory "x1-x5 connectors". The truck is a stock 1986 2wd with the factory harness firewall fuse block.
I have completed the wire as described below.

(2) red ('86) power wires = connected to '13 fuse box (x7 &x8 connections)
(1) pink ('86) distributor wire = to '13 (5) pink ignition 1 voltage wires (x5 connector at fuse box)
(1) purple (86) starter wire = to '13 purple starter wire (x2 connector - engine harness at fuse box)

I have followed the wire pinout diagram description from LT1swap (Brendan). The only wires that I can tell that do not end (power or relay/fuse) at the '13 fuse box are the following.

pin 9 ltblu/wht circuit 383 = blu wire from '86 TCC brake switch (separate grommet on '86 firewall).
pin 50 dkgrn/wht circuit 465 (sends power signal? to x3 connector-grey wire) = '86 fuel tank ('87 switch) power wire at dash
pin 68 brn/wht circuit 419 (cel/mil) = dakota digital brain box.

Any help would be greatly appreciated.
rodstored-72

Re: Engine wiring question(s)
 

So you are saying that the starter does not engage and turn the motor over? What transmission? Possibly a neutral safety switch issue? Are you sure the starter works?

Re: Engine wiring question(s)
 

thanks for the reply, I believe everything works parts wise. I am not sure how to check neutral safety switch? could be, trans is stock 4L60E OG to engine. i thought also maybe the brake valve (brown/tan wire)?
thanks

Re: Engine wiring question(s)
 

Check for power at the purple (86) starter wire when trying to crank. If no power probably neutral safety switch. Did you try cranking in neutral instead of park? Also try moving your shifter while trying to crank to see if neutral safety switch may be out of adjustment.

I ran my stock purple wire directly to the starter.

Re: Engine wiring question(s)
 

back to the top...:smoke: well some good news... some bad news. good news is that the truck will act as wanting to start... I can "bump" the engine and it seems to want to start. the bad news is that I can not get my obdii port to read the ECM?? the port sees power & I believe that I have it wired correctly, but the software will not see/read the ECM?? I have started a separate thread in the electrical section if anyone might have suggestions...:metal: :ito:

Re: Engine wiring question(s)
 

So the OBD is not wired with factory routing? If you installed it yourself and the plug or connectors are aftermarket, you not be making connection. I would test for continuity when plugged up.

Re: Engine wiring question(s)
 

jj,
I have the factory "serial data access wake up" LScanbus wire (dkblu), the (2) HScanbus data wires (2500 & 2501) tan & tan/blk wires, and a 12v+ red/wht stripe wire and the (2) ground wires connected. the tuner software recognizes the power, but does not see the ECM. the port is itc billet made for the "newer" GMcanbus with the GM 6 wire pigtail. the wires are traced from the OG "x109 connector". More detail in my thread in the electrical section as well......

Re: Engine wiring question(s)
 

Well…after more research & talking with my friend with the hp tuner software I FINALLY figured out the correct pin assignments to read the ECM!... woo woo!! Below is the obdii port pin out. This is for a E38 ECM from a 2013 chevrolet Silverado.
Pin 1 thru pin 3= empty
Pin4= signal ground
Pin5= chassis ground
Pin6= ECM pin28 (2500) tan/blk canbus(+)
Pin7 thru pin13= empty
Pin14= ECM pin27 (2501) tan canbus(-)
Pin15= empty
Pin16= batt. (+) const. power
For me I used pin J5 from the “X4” connector (640) red/wht wire for pin 16.
I hope this will be a help to others and thank you all for the replies.
I have been able to "bump" the engine, hopefully to prime the oil areas since it has not run for 2.5 yrs. hoping that in a few weeks I can fill the fluids, put some gas in it & fire it up.

Re: Engine wiring question(s)
 

I am going to post this info in here instead of starting a new thread as I think it is kinda related....

my current problem was I could get my code reader to read sometimes... but my dakota digital dash BIM would not communicate at all. The engine runs fine and all engine systems (sensors) are working properly. After a few days of investigating I was able to determine that the newer engines run a CANBUS network and it requires a 120ohm resistor at each end. My issue was a 120ohm resistor at the ECM plug only (I needed another resistor at the end of the canbus). This past weekend I bit the bullet & with guidance from friends (far more electrical knowledge than I) I de-pinned the data wires from the OBD2 port (my end of the canbus) and after gently "de-skinning" a portion of both wires I soldered a automotive 120ohm resistor a few inches from the OBD2 port termination. I checked the ohm reading at the ends and was consistantly reading the required 60ohm +/- of which I was:62.3- 62.5 ohms. I plugged the BIM module in & reconnected the power, I turned the key on and the gauges all appear to be working..... WOW!! RELEIF! I started the truck & all the gauges were operating. I then coated everything in "liquid electrical tape" and then wrapped that in regular electrical tape. I started the truck again & the gauges are still operating correctly - I also connected the code reader & it also connected right away.... relief!...LOL!
so summarize: if you have a genIV engine with a (X38 ECM) then you will need to have 60ohm +/- at the OBD2 port. and will need 2 120ohm resistors each end of the canbus network. I believe(??) there is 1 resistor at the ECM plug- but not 100% sure.
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I hope that others will find this a help if needed. although I am gathering that most do not use the OG harness and equipment. ;)

Re: Engine wiring question(s)
 

Dang man! Glad you got it all figured out! Must have been frustrating. GOOD job! AND it's running! Next up?

Re: Engine wiring question(s)
 

yea.. I have LEARNED ALOT on this "easy LSswap" LOL!!! The biggest thing is that a genIV setup is a bit more intense than a more common gen I-II swap - a few more wires to deal with that (to me) are pretty important!...LOL! I am on the tail end of my build now & just have a few touch up items to get it it to emissions and then road legal.

thanks for the word...:metal: