P/N safety switch won't work

[gup72]

I have a 2007 LQ4 with a 1997 4L60e combo. Everything works perfect except for my neutral safety switch. When I say everything works perfect, I have driven it over 1000 miles with no issues at all. It will start in any gear and I need to fix this. I have a B&M megashifter with the switch mounted on the side. One side of the switch is grounded. The other side has wire#34 from the C1 blue connecter out of the PCM ran to it. I have P0850 in the DTC's turned on. DTC P0705 is turned off as my tranny doesn't have the switch mounted on the side of the transmission. I have tested the switch and the contacts work as it should.

Any advice would be appreciated!!

[gup72]

Here is the file if someone is willing to take a gander.

jeepwith4l60esegswapRevM.hpt

[gup72]

could it be a quirk with the segment swap?

[mecanicman]

You don't have it wired up correctly. This is the logic for the switch, you would need to provide power and ground in different sequences for it to work. You could wire it up so a relay did it based on your b&m switch, but why not just Put a range switch on trans?
Signal order
A
B
C
P

Park (P)
LOW
HI
HI
LOW

Reverse (R)
LOW
LOW
HI
HI

Neutral (N)
HI
LOW
HI
LOW

Drive 4 (D)
HI
LOW
LOW
HI

Drive 3 (3)
LOW
LOW
LOW
LOW

Drive 2 (2)
LOW
HI
LOW
HI

Drive 1 (1)
HI
HI
LOW
LOW

[gup72]

Thank you MechanicMan. I have read on lt1swap.com that the pcm can be flashed to accept the f body single wire p/n safety switch. Can this be done?

[mecanicman]

As far as I know you have to run a fbody os to do that which would require repining your harness.

[gup72]

I was afraid of something like that. My trans doesn't have the extended selector shaft to accept the factory switch. My PCM isn't the right one to do the single wire. I guess I will see about the relay option. It seems to be the best option.....

[Ranger6202]

why not get an oem switch. correct me if i'm wrong, but the 4l80 and 4l60 have the same switch on the side with the shift shaft through it. Worse case is that you have to upgrade how long the shift shaft is, but i don't recall, its been sometime that i read how to do that. but that would be more straight forward and apples to apples as far as the tune and wiring goes.

[mudntrail]

You don't have it wired up correctly. This is the logic for the switch, you would need to provide power and ground in different sequences for it to work. You could wire it up so a relay did it based on your b&m switch, but why not just Put a range switch on trans?
Signal order
A
B
C
P

Park (P)
LOW
HI
HI
LOW

Reverse (R)
LOW
LOW
HI
HI

Neutral (N)
HI
LOW
HI
LOW

Drive 4 (D)
HI
LOW
LOW
HI

Drive 3 (3)
LOW
LOW
LOW
LOW

Drive 2 (2)
LOW
HI
LOW
HI

Drive 1 (1)
HI
HI
LOW
LOW

Should any wire on the second connector be used, besides the ground wire? Having a similar problem w p0705 I believe this is disabling 4th gear if I start it with switch in d4. Same situation 4l80 with no shift shaft length to mount to trans.

[Jon S.]

Here is the file if someone is willing to take a gander.

jeepwith4l60esegswapRevM.hpt

Missed this thread somehow ... your tune is not setup correctly to mimic a Camaro PNP. See attached PDF.

[gup72]

Thanks for all the information.

Jon S,
I changed it to "none" and flashed the PCM. I have tried turning the DTC P0850 for "P/N input circuit" both on and off with no change in how it acts. It still starts in any gear. The platform is still set to "GMT 800" because if I change this it will cause other issues as far as I understand?

[Jon S.]

How is the starter solenoid circuit wired ?

[Lextech]

You are describing the "Trans Range Switch" The wires and PCM setting you are describing have nothing to do with the engine starting in any gear. That is a "Neutral Safety Switch" issue.

Jeff

[gup72]

The issue is the LQ4 vehicles used the range switch as the neutral safety switch. I am trying to figure out how to have the neutral safety switch with a single wire input. My shaft on the tranny isn't long enough to accept the stock range switch.

[gup72]

Jon S.

Can you be more specific with what you are thinking?

Thanks,
Jon

[gup72]

Can't believe I didn't say this sooner.....

My case doesn't have the mounting bosses for the stock switch. No way to mount one easily.

[Shopboyz]

Assuming you are using the factory 07 Underhood Fuse Block and wiring as far as the starter circuit is concerned, the your B&M mounted switch just needs wired in series with the power wire on the control side of your starter relay. There are a couple other options you could use, but without knowing how you are wired up now it's hard to say exactly what way is easiest for you.

Maybe this will help:

07 Silverado Starter Schematic.gif

[gup72]

Got it fixed. Wired the relay to use the switch as the ground. Put the relay in series with the purple wire going from ignition switch to starter relay. Was easy and works great.

[Shopboyz]

Glad to hear it