Neutral Safety Switch Questions
It looks like this.
It appears that:
wire 1 is the clutch start sw signal.
wire 7 is grnd.
wire 9 is the park/neutral signal.
wire 10 is backup lite power.
wire[s] 11&12 are ign voltage.
In looking at the schematics, it would indicate to me that if the sw is eliminated, then the start relay is going to be inop, and the starter won't engage..[??]
I see U R looking at a T-56. Maybe look at that wiring too, and see if you could do something until the trans is changed??
My combo is going in a 55 Chevy, so I'm going to eliminate that sw/harness, etc, and use the oem, column mtd N/S sw...
1
GY/BU
275
Park Neutral Position Switch Park Signal
2
--
--
Not Used
3
YE
1479
A/T Neutral Signal
4
YE/RD
772
Transmission Range Switch Signal B
5
BU/WH
771
Transmission Range Switch Signal A
6
GY
773
Transmission Range Switch Signal C
7
BK/RD
450
Ground
8
WH
776
Transmission Range Switch Signal P
9
--
--
Not Used
10
L-GN
24
Backup Lamp Supply Voltage
11
BN/BU
239
Ignition 1 Voltage
12
GY
434
Neutral Safety Switch Signal
My harness is an 04 and the only wires left on the larger connector is a pink and black.
I guess my question is what wires would I actually need? Is there anything going to the P/N switch that controls PCM functions?
Trending Topics
The Best V8 Stories One Small Block at Time
If you don't hook up the wiring on the selector switch, it will not work at all
If you don't hook up the wiring on the selector switch, it will not work at all
So I guess I still need to use the big plug
The PCM uses the signal to adjust idle speed based on whether the car is in gear or in park/neutral.
As soon as the PCM "sees" the car go in gear it drops the idle speed by around 100 rpm to prevent jerking going into gear, and to prevent tugging at the torque converter.
It can be considered as optional on a swap. As long as the line is left open the PCM will always assume the car is in gear, and will drop to lower rpm when the engine is started. This also causes a much quicker rpm rampdown on a cold engine start.
Some aftermarket wiring harness companies that have no clue as to how the PCM works will wire this line to ground which makes the PCM think the car is always in park or neutral. On some applications this allows some diagnostic tests to be skipped (EGR, purge, etc.) so that these items can be left off without setting a code. The problem is that the idle is too fast then, and the car wantts to pull a little when sitting still, as well as other issues.
The PCM uses the signal to adjust idle speed based on whether the car is in gear or in park/neutral.
As soon as the PCM "sees" the car go in gear it drops the idle speed by around 100 rpm to prevent jerking going into gear, and to prevent tugging at the torque converter.
It can be considered as optional on a swap. As long as the line is left open the PCM will always assume the car is in gear, and will drop to lower rpm when the engine is started. This also causes a much quicker rpm rampdown on a cold engine start.
Some aftermarket wiring harness companies that have no clue as to how the PCM works will wire this line to ground which makes the PCM think the car is always in park or neutral. On some applications this allows some diagnostic tests to be skipped (EGR, purge, etc.) so that these items can be left off without setting a code. The problem is that the idle is too fast then, and the car wantts to pull a little when sitting still, as well as other issues.
Personal experience has shown that there is not much of an issue leaving out the PRNDL. I do notice a quicker ramp down on idle speed (especially on DBW engines) (I would assume high idle on cold startup is to help get the cats up to temp). I've never noticed an engagement problem at all.
I've not had issue on LT1, Vortec 5.3 at all (cable or DBW), unless they had aftermarket cams.



