Drivetrain Tech General discussion of drivetrain for the Ford Ranger.

Cascading switch for A4LD transmission control

  #1  
Old 04-17-2019
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Cascading switch for A4LD transmission control

The Miracle Ranger is coming along. All the exterior lamps work now, and I got 3rd gear, as the vac line to the trans was full of holes.
No Overdrive or TC lockup, either the mice chewed those wires or the sensors are all bad, and the computer doesn't like it
Had a few of these old computer dataswitches lying around the garage. Got it to cascade so as to use one switch to control them all. Was gonna do two switches, but liked the all in one look of the mighty BAFO.



The "coast" function will soon be wired to enable TC lockup while in 3rd gear, it'll be re-labeled "City" or something. Tested it out and fortunately, the trans still works all the way. Its on a long cable so I can set it on the seat. Just used all the top row of the D sub connector wires for one solenoid and the bottom row wires for another, that way the switch can handle the amp draw, since normally these switches only handle low voltage.
 
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Old 04-17-2019
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A4LD didn't have any internal sensors for solenoid control

Just the one 12v wire for both solenoids, and one ground wire to the computer for each solenoid
TCC hooks to pin 53 on computer
3/4 hooks to pin 52

The computer has the speed signal from the VSS(vehicle speed sensor) on speedometer cable, it uses speed and throttle position for TCC Lock up and 3/4shift

Manual control is OK but it does take the "automatic" out of automatic transmission, lol
 
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Old 04-17-2019
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Originally Posted by RonD View Post
A4LD didn't have any internal sensors for solenoid control

Just the one 12v wire for both solenoids, and one ground wire to the computer for each solenoid
TCC hooks to pin 53 on computer
3/4 hooks to pin 52

The computer has the speed signal from the VSS(vehicle speed sensor) on speedometer cable, it uses speed and throttle position for TCC Lock up and 3/4shift

Manual control is OK but it does take the "automatic" out of automatic transmission, lol
I know the computer uses the VSS and TPS for its info, but I had also read that the temp sensor being wrong can cause the TC not to work. Made sense as that's how Chevy did it for the 4L60. An hour long drive, it never went into 4th gear or lock up the TC, never threw an engine code either.

I can just as easily put it back, if I figure out why it never wants to enable the solenoids, the speedo works ok, no idea about the TPS but I know that might not mean anything.

If anything I will have something to drive if one of the other cars goes out, if I'm honest I'm trying to restore its functions while not spending any money, it has been a lot of fun so far.
 
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Old 04-17-2019
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ECT sensor can effect TCC but not 3/4 shift

Faulty ECT sensor will cause engine running issues as well, hard cold start or hard warm start, lower MPG
ECT sensor has 2 wires
Light green/red stripe wire should be 2.5-3volts with cold engine, after warm up it should be under 1 volt, .50-.70 is normal


TPS is easy to test
It gets 5 volts from computer, key on, Brown/wire wire
Grey/red wire is the Ground, at computer

Grey/white wire tells computer position of throttle, .69-.99v, under 1 volt when throttle is closed
.4.5-4.9volt when throttle is wide open(WOT)

You can use a sewing needle to pierce a wire while it stays connected to test its voltage
Grey/white wire should be under 1 volt then as you manually open the throttle voltage will go up, watch for jumping or dropping volts, bad spots, at wide open it should be 4.5v or higher



You can test VSS with a drill
Pull out speedometer gear
hook it to a drill to spin it
Set Volt meter to AC Volts
Hook it up to VSS sensor, there is no polarity, its AC

Start spinning it, higher RPMs = higher AC volts, doesn't go that high lol, should start around .5-1voltAC

Just FYI the AC voltage is not used, its the Sine Wave pulses of an AC signal thats being used, and only 1/2 of it is used
 
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Old 04-17-2019
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Originally Posted by RonD View Post
ECT sensor can effect TCC but not 3/4 shift

Faulty ECT sensor will cause engine running issues as well, hard cold start or hard warm start, lower MPG
ECT sensor has 2 wires
Light green/red stripe wire should be 2.5-3volts with cold engine, after warm up it should be under 1 volt, .50-.70 is normal


TPS is easy to test
It gets 5 volts from computer, key on, Brown/wire wire
Grey/red wire is the Ground, at computer

Grey/white wire tells computer position of throttle, .69-.99v, under 1 volt when throttle is closed
.4.5-4.9volt when throttle is wide open(WOT)

You can use a sewing needle to pierce a wire while it stays connected to test its voltage
Grey/white wire should be under 1 volt then as you manually open the throttle voltage will go up, watch for jumping or dropping volts, bad spots, at wide open it should be 4.5v or higher



You can test VSS with a drill
Pull out speedometer gear
hook it to a drill to spin it
Set Volt meter to AC Volts
Hook it up to VSS sensor, there is no polarity, its AC

Start spinning it, higher RPMs = higher AC volts, doesn't go that high lol, should start around .5-1voltAC

Just FYI the AC voltage is not used, its the Sine Wave pulses of an AC signal thats being used, and only 1/2 of it is used
Great, that should get this figured out, thank you. I kinda wanted to see the overall transmission health before I went probing wires. I have a good meter, it has a frequency counter in it for testing the vss. Only thing I didn't have lying around is the official service manual with the full wiring diagrams.

Which I might need at some point, whoever did the wiring "modifications" also removed two relays and just taped the spade terminals together. One is the A/C cutout, which is long gone and I don't care. The other I believe is the computer, it won't try to start without the wires tied together.
 
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