Hey all,

having some issues with a tps. I installed a new one and it fixed it up for a day or two. Now it came back. I know parts are cheap now days so I’m not opposed to trying another. But there’s no wrong way to install a tps on a 94 with a 4.0?
thanks for any help
Steve

 

Test the wires first

Volt meter
top wire should be 5volts key on
Bottom wire is the ground

So unplug TPS 3 wire connector, turn key on and use volt meter to test the 2 wires, should see 5volts, 4.9 to 5.2v is fine

Turn key OFF
Plug connector back in
Turn key on
Test bottom wire(black probe) with center wire(red probe), should see 0.69 to 0.99volts under 1 volt
Open throttle all the way, hold it open
Should now see 4.5-4.8volts
TPS is OK

Are you getting a 3-digit code?

If so NEVER EVER Google a code number, you need to look up any code on a FULL CODE LIST first
i.e. Computer has 5 TPS codes to chose from, each means something different, so the codes the computer DOES NOT USE, are as important as the one it does use
121 Throttle Position (TP) sensor out of range
122 TP low (possibly grounded or open circuit)
123 TP is/was high or short to power
124 TP voltage was higher than expected
125 TP voltage was lower than expected

 

RonD,

awesome info thank you. I’ll dig into that this week between homeschooling the kids and I’ll let ya know.

as for codes, reading your reply I’m guessing it should be 3 digit codes. I was counting it as 2 but thinking back I think there was a 1 before the 22 and 21. So guessing it was 122 and 121. Tried disconnecting the battery for awhile today then it wouldn’t start. Would the CEL light come on while the engine only cranks? Thanks a ton!

 

Yes, 1993 and 1994 Ranger 4.0l computers used 3 digit codes

Code list here: https://www.therangerstation.com/tec...gitcodes.shtml

2-digit codes wouldn't match up
21 Engine Coolant Temperature (ECT) sensor out of range - ECT
22 MAP (vacuum) or BARO signal out of range - MAP
23 Throttle sensor out of range or throttle set too high - TPS
24 Intake Air Temperature (IAT) or Vane Air Temperature (VAT) sensor out of range
25 Knock sensor not tested (ignore if not pinging)

I would read codes again, you may be working on the wrong part

Yes, the CEL should come on with key on, that means computer is booting up, powering up
CEL should go OFF while cranking, starter motor turning engine, that means computer is "seeing" crank sensor timing pulse, so injectors will start up

Computer(the EEC) gets 12volts with key on from the EEC Fuse and EEC relay closing in the engine fuse box
CEL should come on then

You should also hear the Fuel pump run for 2 seconds at that time, a HUMMMM you can hear in the cab for 2 seconds
If no CEL and no HUMMM then computer is not powering up

 

Ok, I thought it might be only a two code thing, reaaaallly new to messing with obd1.. mostly been a small engine or jet mechanic. So thanks for the in depth answers. So easy question is my ranger a 2 digit or a 3? Also since this is interesting to me when did Ford switch to or from 2 digit codes.

 

Ford didn't Switch on a specific date or dates for the 2 or 3 digit codes
Ford computers are called EEC(electronic engine control) and also PCM(powertrain control module), PCM was used later when automatic transmission control was added to EEC software
EEC-IV models are pre-1995, they can have 2 or 3 digit OBD1 codes, its the software version that decides
1995 Rangers got the newer EEC-V computer which all use OBD2 4 digit codes, and will have a category Letter at the start, i.e. P for powertrain code, B for body code, C for chassis code

You can find 2 digit software used thru 1996 on some Ford Models
And 3-digit as early as 1988

Your 1993 4.0l Ranger computer will, for sure, use 3-digit, as my 1994 does

 

Got it.. so I’m waiting on a meter to do the voltage test. Ole faithful gave up the ghost after many years of faithful service, so I’m just spit balling here. Got it to run and idle good yesterday and today it just cranks. Yesterday’s code was voltage 122 which is a ground issue according to your earlier posts with the codes. Isn’t the pcm/ecm on the left side fender wheel area? I got side swiped pretty good on that side bout a year ago. Kinda wondering if that is what’s up.

 

1993 PCM will be in engine bay drivers side down below brake master between fender and firewall

You need to remove cruise actuator if so equipped
And the large round firewall connector pass-thru, just has 1 bolt in the center
You can see the PCMs 60-wire connector remove the 1 bolt holding it and pull connector off, and there is a Nut above and below where connector was, they hold the PCM in its cavity
Need good wobble/universal to get at that lower one, lol

There is a video of this, Google: 1993 ford ranger PCM removal

 

Mines a 94 well 12/93 but doubt that makes a difference. Doesn’t look hard to get too, at least I’ve got that going for me. Now the CEL light won’t blink just stays on.

random question, what is that big bound thing with lots of wires going into it near the booster on the firewall?

 

That's the cab/engine wiring pass-thru, its a wire connector just a big one
Engine harness on one side, cab harness on the other side

 

Well got test done on the wires and the tps. When checking it with the key off is there suppose to be voltage between two of the wires or one? I know one would be ground then touched the other two wires and on
y one had the 5ish volts. but I with the key on I was getting opposite readings then what you posted. I was getting 5 volts closed and and the under one volt or so open. Pulled the fuses they all look good, grounds and wires look ok on top. Haven’t climbed under yet, heard they’re was a ground for the computer down there. It’s running now don’t know why but for giggles I went and turned the key and she lives.. I let it idle for about an hour, restarting it a few times. Ran fine, going to let it set and see. I’ll update later tonight

 

As long as you got 5v and 1v its good

 

Had it running like crap today, only after a little starting fluid. It stayed running and started up a few times but ran real rough. CEL stayed on while it was running but I can’t get any codes to blink. I seem to have pressure at the FPR, which is good since I changed it on a prayer 🤣 made a big ole mess. How do O2 sensors play in to starting and running? My gas mileage had dropped considerably in the last year, figuring those are bad or near bad. Picked some Bosch ones up at work, they’re easy enough to get to and all. Just have to find the “safe place” I put them so I wouldn’t lose em.

 

O2 sensors can't operate until they are above 650degF so they are not used at startup anytime, if engine was cold then it will take 5 to 8 minutes for them to warm up, if engine was already warm then maybe 2 minutes after re-start the computer will use them
They are also never used at idle or at WOT(wide open throttle)

 

RonD,

thanks for the reply, not what I wanted to hear exactly 🤣 But still good info.
back to the drawing board

 

Just do a compression test on a few cylinders, or if you have a vacuum gauge hook it up to intake and crank engine over, would expect to see 2"-3" of vacuum if compression is good

Had a friend who used the manufacturers stamp on Cam gear instead of the timing mark, both were circles, had compression of under 70psi

 

I’ll get on the compression test soon as I can get my hands on one from work. Sucks having one vehicle and a wife working 12s. Got it running again after a shot of boom juice. Still runs super rough with a strong smell of exhaust. Small exhaust leak near the cats is part of that. Unplugged some sensors while it was running to see if there was any change. TPS no change.. coolant temp.. no change. I remembered that one messed with my timing once so thought I’d try. Mass air flow no change in how it ran either. Took a peak at the mass air flow and it looked clean. I know that’s not a guarantee it’s not dirty given my bad eyes but it looked ok.

gunna pull the plugs after the engine cools. See how those look, they’re not to old and they’re motor craft plugs.. thanks for letting me bounce ideas off of ya.

 

Swapped out the mass air flow cuz when I tested it with the engine sorta running the voltage never moved when I was raving the engine. So now, it starts barley, but without starting fluid at least. But now I got nooooo throttle response. Even doing it manually, with or without the tps plugged in. This is fuuuuun!!

 

I tested my wires.center wire is always over 3 volts now what do I do?

 

Welcome to the forum

Center wire on the TPS I assume?

Would be good to know the year of the Ranger and engine size

Test center wire, key on, when its plugged in and when its unplugged as well and see what it shows

 

I’ve checked the center wire on the tps it never gets below 3.3 volts it does increase to 4.7 volts at wot. Truck idles perfectly without tps plugged in but won’t take a load. plug tps in and it instantly floods and dies.

unplugged key on it reads 0.04 volts. I’m praying you can help me this truck is driving me crazy.

 

#21
[img]data:image/svg+xml;utf8,<svg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 50 50'><circle class='avatar-circle-default' fill='%23b6badb' cx='25px' cy='25px' r='20px'></circle><text class='avatar-text-default' x='49%' y='53%' fill='white' text-anchor='middle' alignment-baseline='middle'>K</text></svg>[/img]
Kooldaddy67 , 3 Hours Ago
Member
I’ve checked the center wire on the tps it never gets below 3.3 volts it does increase to 4.7 volts at wot. Truck idles perfectly without tps plugged in but won’t take a load. plug tps in and it instantly floods and dies.

unplugged key on it reads 0.04 volts. I’m praying you can help me this truck is driving me crazy.

 

So the 3v is coming from the TPS, not the computer

TPS or the connector is shorting out, partially, to the 5v wire when plugged in
Is there a code?

 

I have a brand new (auto zone) tps it does it with booth also it has a reman e bay computer the one I took of I took apart and the 3 capacitors were definitely leaking on the board so I’m pretty sure that was bad. I’ve watched/read 3 different things about pulling ob1 codes but I still haven’t been successful it’s like the check engine light isn’t working properly

 

I told you wrong those numbers was based off me using the engine as a ground. I reread your instructions and when I use the wire on the bottom of the plug as a ground I get 0.69 unplugged and plugged in a get .98 at “idle” and .10 at wot I’m sorry I’m not trying to waist you’re time I’m just learning and making mistakes as I go thanks for you’re time.