Abbott ERA Installation in 99 Cobra Mustang Convertible
I purchased an Abbott ERA Deluxe (ERA) several months ago in anticipation of changing the wheels and tires on my Cobra. Ron and Coop have previously posted installation instructions on the Corral for the ERA. I have taken their excellent text instructions and adapted them to my installation and added some photos to show the details. Several changes were made in my installation to facilitate adjusting the unit and taking it out of service if it dies prematurely. I have added comments and corrections from several people who used these notes to install their ERA units in January, 2000. I appreciate all the comments I received and hope the resulting changes help others. (Updated again during the Super Bowl on 1/30/00.) Note that these instructions are applicable to the 99 Mustang whether GT or Cobra, Convertible or Coupe. Earlier Mustangs may have different wire colors and plug designations. See the appropriate wiring diagram book for earlier Mustangs to see the differences.
The ERA has 4 wires which must he securely wired into the car:
Black wire chassis ground
Red wire +12 volts when ignition is on, NOT hot all the time
White wire
Signal from Output Shaft Speed Sensor (OSS) on the transmission
(Located on rear of trans, driver's side)
NOT vehicle speed sensor (VSS)
Blue wire Corrected Signal to Power Control Module (PCM)
One way to hook up the ERA is to use the hot wire to the radio if you can get your radio out, and extend the white and blue wires to the sensor on the transmission and connect them there. That was too easy. The instructions below are for connecting the ERA up to the OSS wire at the PCM inside the car, and to the console accessory/run hot wire rather than to the radio, which I couldn't get out easily, even with the correct tool.
I planned on using two 2 pin male and female trailer plug assemblies to extend the four wires from the ERA and to extend the wires in the car to the two ERA unit plugs. The plugs would allow the unit to be removed if it failed (not likely, by the way) and the original wiring to be jumpered with a loop plug so the speedometer would work without the ERA unit in service. The colors on the wires shown on the photographs are the colors of the wires to the trailer plugs in some cases and don't always match the color of the wires to the ERA itself. I had to do this because the trailer plugs are usually available in red and white.
I first removed the right side kick panel to get to the PCM. You
must remove the door strip first by pulling it straight up, starting with
the end toward the front of the car. Then remove the plastic pin
down near the carpet at the forward bottom edge of the kick panel.
Then pull the panel straight back in line with the door strip to remove.
Here is a picture of the inside of the kick panel showing the pin and clips
after the panel has been removed..
The OSS wire is in circuit 970 and is a dark green wire with a white stripe which runs from the transducer on the transmission to pin 84 in the PCM.
Here is the cable bundle with the dark green wire cut and the white ERA
wire connected to the end from the transmission and the red plug extension
wire (blue to ERA)connected to the other end going to the PCM. As
you can see, there are plenty of green wires of various kinds in the bundle!!
Note for GT two-valve owners--The GT engines do not have knock sensors, therefore there is no wire on pin 23 in the PCM and there is only ONE dark green wire with white stripe in the bundle. You don't have to go through the decisions on which wire to tie into like the Cobra owners do!!.
Note: Unfortunately, there are TWO dark green wires with a white stripe going to the PCM on the Cobra, not the GT. The other one is from the knock sensor and goes to pin 23 in the PCM. If you accidently hook in to this dark green/white stripe wire, the speedometer will still work but the ERA won't change the vehicle speed reading when you change the dip switch settings. But there won't be any other indication that you have the wrong wire.
There is also a LIGHT green wire with a white stripe going to pin 26 of the PCM. This is the output signal to the coil on the #1 cylinder. If you hook into this wire, the engine won't run right because the #1 cyclinder won't fire and you will think you have screwed up your car terribly. You will not see any change in the speedometer, though, since you haven't tied into the speedometer circuit.
So how, do you ask, can you verify pin 84 on the PCM to make sure you have the right dark green/white wire? The following was provided by Coop99Cobra on the Corral bulletin board....
Well, 1st of all, don't disconnect the 104 pin harness from the PCM (the dealer will know you did this if you do and suspect you tried to chip it).
But if you remove the plastic protective shroud from the 104 pin connector, you will be able to read the pin designation on the underside of the connector. The DG/WT stripe wire (pin 84) is the 6th position from the end of the plug which is towards the front of the car, along the bottom row (4 rows of 26 pins each).
To verify, pins 81 & 82 (3rd & 4th position) are not used, so no wires there. Also, pin 79 is White/red stripe, pin 80 white/red stripe and pin 83 White/light blue stripe.
To make things easier, remove the one screw that holds the PCM in place and gently pull it from its resting place. Then you will be able to turn it as to have better access to the 104 pin connector. Again, you don't have to disconnect the wiring harness from the PCM to do this and I recommend that you don't.
Lastly, just to be sure, you can test continuity between the point you found at the PCM and the source of the wire at the output shaft speed (OSS) sensor on the driver's side of the tranny.
You can barely reach the wire at the OSS and you'll have to remove your shift boot to do it, but it can be done. From the plug diagram in the wiring book on the Mustang, pin 84 (the wire you want) is 6 pins from the end of the plug toward the front of the car and pin 23 (the wrong wire) is 4 pins from the other end of the plug (the end toward the rear of the car).
Some of the tape can be removed from the cable just ahead of the large PCM plug in the kick panel and, hopefully, the correct DKGN/WH wire can be found in the cable bundle. Once found, it can be cut, the ends stripped, and the ERA wires can be soldered to them, with the white wire going to the upper wire, from the transmission transducer, and the blue wire going on to the PCM. These connections are difficult to get to but it can be done. The photo on the right shows the bundle with the finished two pin trailer wiring plug spliced into it. At the bottom of the photo just below the gray plug is a green ground bolt with a new ground lug and black wire going to another trailer plug. Also shown is the blue hot wire extension and splice to the red trailer plug wire. Note--connect the hot wire to a FEMALE trailer plug pin so that the hot wire will not short to something if the car is run without the ERA plugged in. If you connect the hot wire to a male pin, the pin is exposed when the plug to the ERA is removed and it could short to any exposed metal, blowing a fuse.
A suitable hot wire can be obtained by removing the shifter knob and boot and finding the console plug just to the left of the shifter. Find the circuit 296 white wire with pink stripe and connect the red wire from the ERA to it. Do not cut the wire, just remove some insulation and tie into it. The correct wire is in pin 5 in the plug. You can see the pin numbers on the back of the plug if you look carefully.
Note: There is an error in the Ford wiring diagram book on this console
plug. On one page (page 102-1) the wire is described as a white wire
with a pink stripe. On another page (page 150-13) it is described
as a white wire with a violet stripe. Some people have reported a
white wire with purple stripe. Others have reported that the white
wire with the purple/violet/pink stripe looked more tan or gray with the
stripe, not a pure white. The correct wire goes to pin 5 (a peripheral
pin) in the plug and the wire in pin 9 directly below it is a brown wire
with no stripe. The pins are numbered 1-2-3-4 on the top row with
1 at the driver's side edge. The second row is numbered 5-6-7-8 with
the wire you want on the driver's side edge, second wire down from the
top.
I extended the Abbott red wire to reach the console area using a 14 gauge
blue wire. This hot wire is the blue wire in the photo. This
blue wire was tucked in behind the console before the shifter boot piece
was replaced. The wire was then tie-wrapped to the large cable just
under the passenger side dash over to the PCM area. My 13 year old
niece (and future engineer), Lydia, was much better at this task than I!
I used several two-wire trailer wiring plugs at the PCM location to allow the ERA to be easily disconnected. I used one plug for the ground and power wires and another plug for the OSS/PCM wires.
Note that all the connections in this installation were soldered and taped. I also made a jumper that could be inserted in the OSS/PCM plug to use if the ERA quit on me. The ERA itself was wrapped in bubble wrap and dropped in the space below the PCM module. This is one good place to locate the ERA. It is difficult to get to but your ERA sure won't get stolen easily from this location!
The
space below the PCM can be accessed by loosening the black bracket supporting
the gray and green connectors. I test drove the car before and after
putting the ERA into its final position.
When the gear ratio or rear tire size is changed, the kick panel will
have to be removed, the ERA pulled out, unwrapped, and opened up, and the
dip switches set per the required correction factor. Should take
about 10 minutes.
Alternate ERA Location Used 1/30/00
There is another, maybe better, place to put the ERA (first recommended by Maynor) which doesn't require that the kick panel be removed for access. This is the area just below the passenger side heater vent under the dash and behind the console. I had enough wire on my ERA with the trailer plugs to allow me to move the ERA to its final position as shown below.
Here is
the ERA with the trailer plugs and the jumper plug which can be installed
in the upper plug to re-connect the OSS directly to the PCM. The
lower plug is for the ground and the hot wire. I just left the jumper loop with the plug under the carpet where I could
always find it! This way, I don't need some pliers to get the kick
panel off or a nutdriver to get the ERA out from the hole under the PCM
in the kick panel.
Here
is a shot of the ERA wrapped in bubble wrap and stuck in the console behind
the carpet right under the heater vent. The wires run across to the PCM/kick panel area. No tools required to get to the ERA. Probably
should have wrapped the ERA in the instruction sheet with the dip switch
settings so I could find them when I needed them, too!!
Dip Switches
The dip switches in the 4 switch bank in the ERA need to be set as follows:
switch 1 on, switches 2, 3, and 4 to off for all Mustangs.
The 10 switch bank is set for the desired correction factor per the chart in the instructions with the ERA.
The correction for a gear ratio change is calculated by: old gear / new gear = factor
For a change to a 4.10 gear when the stock gear was 3.27:
3.27 / 4.10 = 0.80
To correct for tire size: new tire diam / old tire diam = factor
For 25.96" diam new tire and 25.62" diam old tire:
25.96 / 25.62 = 1.01
To correct both at same time, multiply them together, 0.80 x 1.01 = 0.81
Find this factor in the ERA chart and set the dip switches accordingly. Then go check it like the ERA instructions say and apply any correction to the current setting to get the final setting. I started with a 0.81 setting and had to correct it to 0.83 after the 10 mile test, because the speedometer read 2% low at 0.81.