• Mustang Forums
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-

at a loss

  • Thread starter Thread starter ryan218
  • Start date Start date May 19, 2007

ryan218

In just 10 years, I'll be old enough to drive!!!!
Dec 28, 2005
0
1
38
columbus ohio
May 19, 2007
#1
  • May 19, 2007
  • #1
Justin came over and checked the timing for me...was at 10...so the timing is perfect...he also brought his scanner to pull codes but it wont on my car...works fine on my dads and Justin's stang...but not mine...

could this be a problem with my computer?

Thanks again for stopping by Justin...
 

jrichker

StangNet's favorite TOOL
In Remembrance. Thank you for your contributions
Mar 10, 2000
27,512
2,811
234
Dublin GA
May 19, 2007
#2
  • May 19, 2007
  • #2
Computer will not go into diagnostic mode

How it is supposed to work:
The black/white wire (pin 46) is signal ground for the computer. It provides a dedicated
ground for the EGR, Baro, ACT, ECT, & TPS sensors as well as the ground to put the
computer into self test mode. Since it is a dedicated ground, it passes through the computer
on its way to the computer main power ground that terminates at the battery pigtail ground.
It should read less than 1.5 ohms when measured from anyplace on the engine harness with
the battery pigtail ground as the other reference point for the ohmmeter probe. What sometimes
happens is that it gets jumpered to power which either burns up the wiring or burns the trace
off the pc board inside the computer. That trace connects pins 46 to pins 40 & 60. Only an
experienced electronics technician can open the computer up & repair the trace if it burns
up and creates an open circuit.

The STI (Self Test Input ) is jumpered to ground to put the computer into test mode. Jumpering
it to power can produce unknown results, including damage to the computer. The ohm test
simply verifies that there are no breaks in the wiring between the test connector and the computer input.

How to test the wiring :
With the power off, measure the resistance between the computer test ground
(black/white wire) on the self test connector and battery ground. You should see less than
1.5 ohms.



If that check fails, remove the passenger side kick panel and disconnect the computer
connector. There is a 10 MM bolt that holds it in place. Measure the resistance between
the black/white wire and pin 46: it should be less than 1.5 ohms. More that 1.5 ohms is a
wiring problem. If it reads 1.5 ohms or less, then the computer is suspect. On the
computer, measure the resistance between pin 46 and pins 40 & 60: it should be less than
1.5 ohms. More that that and the computer’s internal ground has failed, and the computer
needs to be replaced.

If the first ground check was good, there are other wires to check. Measure the
resistance between the STI computer self test connector (red/white wire) and pin 48 on
the computer main connector: it should be less than 1.5 ohms. More that 1.5 ohms is a
wiring problem

The following is a view from the computer side of the computer connector.


Diagram courtesy of Tmoss & Stang&2birds



See the following website for some help from Tmoss (diagram designer) & Stang&2Birds
(website host) for help on 88-95 wiring http://www.veryuseful.com/mustang/tech/engine

 

ryan218

In just 10 years, I'll be old enough to drive!!!!
Dec 28, 2005
0
1
38
columbus ohio
May 19, 2007
#3
  • May 19, 2007
  • #3
ok ill try that later...i feel like complet **** at the moment...****in alerages....me and shane replaced the injecots and it helped a little bit but still has a miss
 
You must log in or register to reply here.

Similar threads

Z
Progress Thread zeth194 - New Guy on the Block
  • zeth194
  • Mar 19, 2026
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
Replies
10
Views
438
1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk- Apr 26, 2026
LILCBRA
P
2000 GT Random Power Loss
  • Pinellas50
  • Mar 9, 2026
  • SN95 4.6L Mustang Tech
Replies
4
Views
240
SN95 4.6L Mustang Tech Mar 23, 2026
Pinellas50
P
S
Computer repair advise
  • sammie9271
  • Jul 28, 2025
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
Replies
18
Views
728
1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk- Aug 2, 2025
Parauno
P
K
Electrical 2000 GT Intermittent Engine Shutdown In Motion - DTC U1262
  • kenster1092
  • Apr 13, 2026
  • SN95 4.6L Mustang Tech
Replies
4
Views
131
SN95 4.6L Mustang Tech Apr 24, 2026
squeak93
89 LX Electrical Troubles
  • fun331
  • Oct 25, 2025
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
Replies
5
Views
322
1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk- Nov 27, 2025
fun331
Share:
Bluesky Email Share Link
  • Mustang Forums
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
Menu
Log in

Register

  • Forums
  • What's new
  • Media
  • Resources
  • Contact
  • Sponsor
X

Privacy & Transparency

We use cookies and similar technologies for the following purposes:

  • Personalized ads and content
  • Content measurement and audience insights

Do you accept cookies and these technologies?

X

Privacy & Transparency

We use cookies and similar technologies for the following purposes:

  • Personalized ads and content
  • Content measurement and audience insights

Do you accept cookies and these technologies?