Wiring help from my mustang brothers

Lugnuts · Jul 18, 2011

I need someone with a "98 GT 5-speed to take a look at the wiring harness under the hood on the passenger side between the strut tower and the windshield. There should be a round plug (some are white and some are black). I need to know what position the white wire with the black strip is going into.

Converted auto to manual and losing 3 wires - original had two white with black stripe wires and now will only have 1 white with black stripe from the new harness. Need to know which one stays and which one goes.
Thanks guys.

Lugnuts · Jul 19, 2011

This is a picture of the plug in question. Black plug is the stock auto plug and has the following wires:
blue w/black stripe
red w/ green stripe
purple w/ white stripe
white w/black stripe
yellow w/black stripe
another white w/black stripe
brown w/ yellow stripe

The new manual harness is the white one with these wires:
purple w/ green stripe
red w/green stripe
white w/ black stripe
brown with yellow stripe

Anyone have a wiring diagram and can tell me what these wires are? I need to sort this out, find and wire my neutral safety switch (one of these maybe?) and fix my reverse lights and the swap will be done.

Anyone?

wmburns · Jul 19, 2011

Helping where I can. I think the round connector in question is C119. For some reason, my Ford reference does not include the connector face for C119. Tons of other connectors.

I might be able to piece the wire colors from the the diagrams. But the diagrams don't always include the pin #'s. Nor are they all together in one place. It will take quite some time to review the diagrams to get the information.

The 96+ MY manual Mustang does NOT have a neutral safety switch. It uses instead a clutch safety switch. The clutch must be depressed before the starter motor will work.

The automatic transmission safety switch is on wire W/PK and RD/LB. My diagrams indicate these wires pass through connector C106 which is a square connector. There does appear to be a jumpper in connector C106 to bypass the automatic safety switch on manual cars.

Note, C106 is a square connector. So you might be looking in the wrong connector. Try looking for a W/PK (pin 2) and RD/LB (pin 3).

The problem here is the wiring diagrams have different versions for automatic vs manual. And some of the colors are used for different things in the two versions. However, likely what you need is a jumpper between the W/PK and RD/LB wire in the square C106 connector.

Lugnuts · Jul 19, 2011

Good to know - thanks for your help. Please post me with all info on the clutch safety switch and neutral safety switch that you can. I still need to find out what the round connector is and it's connections. Appears that pre 98 manual used this as strictly for O2 sensors and 98+ auto used it for O2s and shifter position.

I traced the wires on the auto harness and:
blue/black wire goes to the shifter position sensor
red/green wire goes to a rearward O2 sensor
purple/white wire goes to a rearward O2 sensor
white/black goes to the shifter position sensor
yellow/black goes to the shifter position sensor
white/black goes to a rearward O2 sensor
brown/yellow goes to a rearward O2 sensor

The new manual harness wires on the round plug all go to O2 sensors. The question here becomes what to do with the rest of the original wires that went to the shifter position sensor.

The manual transmission harness has a jumper in it from one terminal to another in the square connector. I just need to verify if this is a closed loop for the neutral safety or if it has to do with the shifter position wires in the other plug.

For info purposes, my car is a 1998 GT and the donor for the manual was a 1998 (early year - assembled in 97) Saleen Mustang. I have run into a couple other 1998 year specific electrical/electronic issues that have been painful. Appears that 1998 was a bastard year - they started some changes but did not finish them up until 1999 model year so nothing seems to be direct swap from pre 98 or post 98.. The 4R70W I took out is a prime example - all electronics except speed are more like 99+ and speed is like pre 99. Got a 97 built trans and had to take it apart to put all 98 electronics in it so it would plug up to harness. Had a shot at a 99 but the speedo would not run with 99+.

Lugnuts · Jul 20, 2011

Okay, I have determined that of the 7 original wires, 4 are for O2 sensors and 3 go to the shifter position sensor. Looking up parts, they call this the neutral safety switch. Someone on this forum must have done this conversion before and knows which wires I need to jump together to indicate neutral.
Please advise ASAP.
Thanks guys.

wmburns · Jul 20, 2011

I gave you the information on how to bypass the automatic park/neutral safety. Put a jumpper between C106 WH/PK (pin 2) and RD/LB (pin 3). This will complete the circuit for the starter to work.

Lugnuts · Jul 20, 2011

Thanks. I have put the jumper in like you suggested and was trying to figure out what the other 3 wires are going to the shifter position sensor. I will try to run without it and see what happens.
Will let you know.

wmburns · Jul 22, 2011

Lugnuts said:
blue/black wire goes to the shifter position sensor
white/black goes to the shifter position sensor
yellow/black goes to the shifter position sensor

The 1998 MY transmission diagram 029-003 indicates there are (3) wires going through connector C119 for the Digital Transmission Range (DTR) sensor.

Y/BK, LB/BK, W/BK.

All are associated with letting the PCM "know" what position the DTR is in. So I would think those are no longer needed.

The electronic engine control diagram 024-007 indicates the follow wires go through connector C119 for the rear O2 sensors.

T/Y
P/LG
W/BK
R/LG

I didn't catch that the new manual harness already has a jummper between pins 2 and 3. So that should make the starter safety work.

The backup lights are covered in diagram 093-001. The diagram indicates the back up lights go through the same set of connectors. This is were it gets confusing. The diagam calls out connector C106. Which is a square connector that looks like C119. The wire colors are P/O and BK/PK. However, it looks like the pin assigments are the same between auto and manual. So it doesn't seem like there is anything to do for the back up lights.

Cir# pin# color
298 01 P/O
140 04 BK/PK

Lugnuts · Jul 27, 2011

Thanks wmburns!
I took your info, traced some wires and she is a runner!
I still have a couple things to sort out - the back up lights still do not work and I have yet to identify and route the starter kill through the clutch switch but neither makes it yard art - and it is too fun to park long enough to worry about right now.
Totally different personality with the T5. Already had steep gears in the back end and the final drive ratio may be a bit much now as 1st gear is almost unnecessary and 5th is usable cruising around town! Definitely not a highway car right now but the torque is even more than I anticipated from a little mod motor. I have 10" DOT drag radials on it and when cold I can spin 'em from 1st up into 4th (just for fun). Proper burn out and launch makes for some fast shifting and loads of fun! Anyone need any 4R70W stuff cause it is not going back in - ever!
For any other swappers, the round connector that I had a problems with is going to have to be changed. You can re-use the 8 pin (98) or 4 pin (pre 98) but you will have to re-pin the plug for your rear O2 sensors (unless you have them turned off). The other 3 wires that went to the auto trans shifter position sensor will not be used. I checked a number of cars around here and it appears that 2000+ cars do not have this plug and some 99 do (8 pin) while some 99 don't have this plug at all.

Thanks everyone for your input! If you are ever in Augusta, let's run!

wmburns · Jul 27, 2011

That's great to hear.

On your back up circuit, suggest that you start by confirm I/P fuse 1.

Next, disconnect the back up light switch at the transmission (C161). Confirm +12 volts to the P/O wire with the key on.

If no power, we need to look for a fault between the fuse and the C161 connector.

Measure the resistance of the backup switch itself. Should be low when in reverse and open when not.

The switch closes when in reverse. If not, there's where the problem is. Confirm by shorting the P/O and BK/PK wires together and confirm that the back-up lights come on (key on).

Measure the key off resistance of the BK/PK wire to a known good ground. This should be reading the resistance of the back-up light bulbs.

If open, that indicates a open in the wire path back to the bulbs.

If it appears to be a reasonable value for light bulbs, try injecting +12 volts to the BK/PK wire and see if the back-up lights come on.

Will go from where the tests point.

Wiring help from my mustang brothers

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