These sensors are driving me nuts.

[soul_justice]

Hey guys, long time lurker first time posting. I've been having a sensor problem with my ranger for a while now that's driving me crazy. All the sensors except for anything EGR are brand new and test out with respect to resistance. Without further ado, here's my fault codes-

Continuous codes
23 TPS out of self test range
33 EGR valve opening not detected
51 ECT indicated -40F or circuit open

KOEO codes

81 secondary air injection diverter failure (WTF is this???)
93 coast clutch solenoid failure

Three digit codes

113 IAT above max voltage/-40F indicated
118 ECT circuit above max voltage/-40F indicated
121 TPS voltage inconsistent with MAF sensor
123 TP sensor above max voltage
337 EVP/PFE circuit above max voltage
341 octane adjust service pin open (WTF again)
519 PSP switch circuit open

I haven't even gotten to koer codes yet. The power steering switch is open because my steering box has a massive leak and dumps PS fluid as soon as I pour it in. Otherwise, all the other sensors are new. I tested the TPS voltage yesterday and got something weird like -1.6v. I will check again here shortly and update. This value didn't change when operating the throttle blade. Also the EGR valve itself still works, I applied 15 in-hg of vacuum to it and the truck acted like it wanted to stall.

So my questions are as follows-

As long as the CEL is on do none of these sensors operate?
Will a bad EVR sensor keep these sensors from operating?
Why the F am I getting a smog pump code (AIRD)??

I'm trying to get this truck in optimum shape, right now I'm getting about 300 miles to a tank if I'm lucky and I drive 700 miles a week. I'm pretty handy with tools, have a multimeter, and Ford engine/chassis/EVTM/powertrain and emissions manuals.

Thanks for any help you can provide.

edit- I also cannot pull codes except by jumping the STI to ground and reading check engine lights. I find this suspicious since all these things including the test harness share a signal return (gray with red stripe) wire.........

Edit #2- I have continuity between the TPS, ECT, IAT, EVP, the Data Link Connector, and pins 46/49 on the PCM wiring harness, so it's not a break or short in the wiring. In fact I tested all related components in this to their respective pinouts on the wiring harness and everything shows that it is continuous, including the PCM shorting bar.

 

[RonD]

Good 1st post

The PCM references and controls everything by Grounds.
So I would pull out the PCM and check all the ground pins on the connectors.

I would suspect a problem with the PCM if all the Grounds are good.
You can pull the cover off the PCM and have a look inside, it is way past any warranty
As far as I know there is no way to home test a PCM.

Yes, if PCM is running engine in Open Loop all the time then MPG would be low.
And if EGR was not opening then engine would be "pinging/knocking" under load, unless it was running too rich.

I would test the ECT sensors voltage or ohms just to confirm it is a PCM issue not a sensor issue.
To test voltage I use sewing needles to penetrate the wires then use the meter probes on the needles.
ECT is a pain to get to on the 2.3l so I would test voltage at the PCM end.
Specs are here:
http://oldfuelinjection.com/?p=28

That site also has specs on other Ford sensors

 

[soul_justice]

I did some further testing on two sensors- the ECT and TPS. Note that while I'm inexperienced with Ford EFI I'm not retarded and know how to use a multimeter. I say this not to offend anyone but because if someone told me what I'm about to describe I would say they had their test pins backwards.

ECT pin to pin (black on sig rtn, red on grn/r) -.28v/1568 ohms
ECT green/red to chassis ground +6.47v
TPS sig rtn to vref (black on gray/red, red on brown/white) -1.69v
TPS VREF to ground +5.08v
TPS sweep to sig rtn (red on gray/white) -.17v
TPS sweep to ground +6.6v

None of the TPS values changed when operating the throttle. I'm gonna pull the TPS off next and leave the connector on and operate the sweep myself to see if I can get any voltage change.

These tests were performed with a good multimeter. I've never gotten negative voltages on a circuit that I was supposed to get positives on. Maybe the pcm IS bad.

 

[RonD]

Both the ECT and TPS are 5volt sensors, so I would guess the Voltage regulator inside the PCM or it's circuit is bad.
This would give you the -40 ECT and TPS out of range codes.

Yes, my guess would be bad PCM as well

 

[soul_justice]

My local pick n pull has 5 rangers 89-93 and I know at least one is a manual, so I'm going to go see if I can find a pcm that matches mine. Only $25 so I figure I can't go wrong. I pulled the pcm out of my truck as well to match everything up too, it looks original and from searching around the part numbers seem to match up with what other people have pulled from 2.3 5 speeds, but just in case I'll list it here anyway. I'll report back once I find another pcm and get it installed.

B002
F37F-12A650-BC

I think a bad PCM would also explain the weird codes I occasionally get like the AIRD solenoid code, octane switch code, and I think I even got a boost solenoid code once... If only the pcm thinking I had a 2.3 turbo made it true

Both the ECT and TPS are 5volt sensors, so I would guess the Voltage regulator inside the PCM or it's circuit is bad.
This would give you the -40 ECT and TPS out of range codes.

Yes, my guess would be bad PCM as well

 

[scotts90ranger]

You'll need a '93-94 ECM for your engine for a direct replacement, '89 and early '90 didn't have a MAF, late '90-92 had a MAF but no DPFE, some late '94 and all cali '94's had cam sensors

just to help you narrow things down... you could probably use an earlier MAF ECM and be fine, but you'd probably get the EGR position code...

 

[RonD]

The Ford part number for ANY PCM is the 12A650 number in the middle

F37F should be the model year and vehicle info

BC is the Supplier number and it's version number

There is usually an added sticker with the software version, maybe the B002??

This is a good read as well about PCMs:
http://oldfuelinjection.com/?p=17

 

[soul_justice]

Gotta love one-off years. Is there any way I can narrow it down to it being a bad PCM short of it catching on fire? I pulled it out earlier and didn't find any damage or busted capacitors. The local JY didn't have any usable computers, so I'll be expanding my search tomorrow. Fleabay has some but of course they want an arm and a leg for them, so if I can't find my specific year in a yard I'll have to get it from there... But $130+shipping is a tall order for something that could be as bad or worse as mine, and it's even harder to swallow that I don't know if mine is shot. I feel it is, I just wish I knew something more concrete.

You'll need a '93-94 ECM for your engine for a direct replacement, '89 and early '90 didn't have a MAF, late '90-92 had a MAF but no DPFE, some late '94 and all cali '94's had cam sensors

just to help you narrow things down... you could probably use an earlier MAF ECM and be fine, but you'd probably get the EGR position code...

 

[scotts90ranger]

The only other thing that would cause multiple sensor codes is a bad power or ground supply to the ECM, check any grounds near the ECM, look at the terminals at the connector to see if any look corroded or anything, and check the engine grounds themselves.

I think even Napa would beat that ebay price, ebay isn't as good of a deal as it used to be... I have a spare working '89 ECM I'd get rid of for cheap but it wouldn't run your engine well as it's set up to use a MAP sensor not MAF...

 

[soul_justice]

I'll definitely be going the napa route, I'm definitely not gonna pay that much for a used pcm from egay. Rockauto had refurbs for 100+core, but napa does have them for 100 with no core, so if this doesn't solve my problem I may be able to return it.

I'm a poor broke white boy so I won't be able to get one til Friday but I'll definitely post my results when I get the new one in.

The only other thing that would cause multiple sensor codes is a bad power or ground supply to the ECM, check any grounds near the ECM, look at the terminals at the connector to see if any look corroded or anything, and check the engine grounds themselves.

I think even Napa would beat that ebay price, ebay isn't as good of a deal as it used to be... I have a spare working '89 ECM I'd get rid of for cheap but it wouldn't run your engine well as it's set up to use a MAP sensor not MAF...

 

[soul_justice]

It was indeed the computer. I swapped out the old one for the reman unit this morning and voila, everything works as it should. Drives and idles ten times better now. Thanks to everyone for their help!

Now I can start on rebuilding this toasted 5 speed trans I pulled out last month...