NV3550 to 32RH 2003 TJ wiring help

Read this...


-Mac

The 3 pin connector is for the speed sensor at the transfer case. Won't get anything useful there.

The Weatherpacks are the transmission back-up lamp switch and the transfer case 4x indicator.

The manual transmissions for 2003 have a dedicated starter relay ground. 97-02 did it a bit different where the body wiring (ign power, back-up feed, starter relay ground) all came to that 5 pin connector (known as C154 in those years) and then the manuals and autos had different jumper harnesses (NSS for auto, reverse and a ground loop for manuals). That allowed them to build most of the wiring the same to the transmission and then just use the different jumpers and satisfy both transmission options easily at assembly. Basically, the auto version rerouted the starter relay ground and the ign/back-up feed wires to the NSS, while the manual version routed the ign/back-up feed wires to the back-up switch and looped the ground to ground the starter relay all the time (because they control starting with the clutch switch by controlling the power side of the relay).

2003 does it a bit different, where the starter relay ground on manuals originates from a splice and then goes to another splice and to a ground point. There is no more C154 connector, so there is nowhere to plug in that 5 pin harness you have. Basically, you need to go upstream and find the starter relay ground (somewhere between S134/S132/G105), and you need to reroute that to the 32RH NSS pin 2 so that it interrupts the starts.

And you need to reroute the two wires from the back-up lamp Weatherpack to 32RH NSS pins 1/3.

Hope that helps.

Locations for S134, S132, and G105 if it helps. Might help you figure out where to grab that ground wire from nearby. Need to find the one that goes back to the relay, though.

JC-8 said:

Macho,

When you mention grab that wire.... do you mean to actually pull the wire and pin it in center location between the 2 reverse wires?

That would than be the ground connection for the starter relay.

Could I cut the ground loop and run a new wire from relay and pin it ?

Click to expand...

The starter relay ground is circuit T41. It serves two places: the starter relay in the PDC, and it also has a branch running to the PCM so that the PCM knows the status of the relay ground at any time. The PCM is on the engine harness, the PDC is on the engine compartment harness.

T41 from the PDC side goes to C104 as a brown/light blue wire. C104 is where the engine compartment harness hands off to the engine harness. It comes out of the engine harness side of C104 as a black/white wire. The two T41 wires (brown/light blue from PCM, black/white from PDC/C104) merge at splice S134. So you will want to cut downstream of that.

Then the manual transmission version of the circuit goes into S132 which ties T41 to a bunch of other permanent grounds, and then they all ground together at point G105.

Basically, you want to find the wire downstream of S134 and cut it before it runs into S132, and extend the S134/PDC/PCM portion down to the NSS pin 2.

JC-8 said:

Macho,

In your opinion will the motor start w/o that ground into the NSS?

And thanks for the very detailed help, much appreciated.

Click to expand...

If the starter relay is grounded, which it is by default according to the diagram for manual transmission '03s, then yes, it would start up without doing anything (assuming you have bypassed the clutch safety switch). I would definitely suggest wiring it up to work as intended though, don't want to start it up and it try to run away.