My mistake. (late in a day of 100* temps) It actually was 452 & it was a CM from the first test drive with a replacement computer.

 

Then I would say with your symptoms you need to check the signal from the PSOM to the PCM. You could look at this signal train with a scope.


Could be a bad speed control, try unplugging it and see what happens. Also clear the code first. If the code returns change the PSOM.

The VSS, wiring from the VSS to the RABS and PSOM, along with the RABS module should be OK with a steady needle at the speedometer. The steady needle at the speedometer says the the signal train to PSOM from the VSS is OK.

 

Thanks.

Silly' scopes are a bit had to come by right now unfortunately.

The speed control is where/what? I'm somewhat at a loss on that except for the CC.

Also, PSOMs are not generic across powertains, years?

 

The speed control unit:


Not sure what you mean by CC.

The PSOM:


/

 

Yes, when you said "speed control" the cruise/speed control servo was all I could think of. (CC)

I have a pair of PSOMs, from a 300, one from a diesel, years unknown save for older than 92. I'll see if I can narrow down their dates if they need to be used.

I'll pull it off the jack stands this AM rather than doing the AC volt test with the PSOM unplugged, clear the code & test drive with the speed control unplugged, then report.

Thank you very much for the valuable assistance.

 

If a PSOM is older than 1992 it did not come from a truck. Only cars had the PSOM before 1992.

Ford did not use the term "cruise" in the 1990's only speed control as in the diagram below.

A diagram of your VSS wiring:


/

 

Had a look at the boards I have on hand. I'll use the one from the 95 or later diesel first (board # starts with F5) for testing purposes. The 6's board #s start with F3 so it could be anything 93 & later.

 

For the first time since I decided to have my E4OD rebuilt, I feel like I can breathe just a bit easier.

With servo unplugged the transmission shifts 99% the way I think it should (and what I paid for) over the short test course That I run. That last percent, I think is the computer learning its tables & the business of running the trans just got in the way. No PSOMs were used.

Running the codes came back with 111/111 KOEO/CM.

Engine Running came back with expected 311 air injection code (pump & plumbing deleted) that had long disappeared off the old computer (stopped recording it sometime back) and a 538 failure to floor it quick for the computer. I never have been fast enough for it.

I'm still having some heat soak issues with my starter or battery issues I'm trying to sort through. But even that was much improved after my last test drive.

Suppose I'll start looking for a replacement servo.

Thank you for your time & attention. As always you've been a great help.

 

Update:

After a a couple of weeks of short trips averaging 10-15 miles in town and a couple passes down I-20 with no issues, I decided to pick up a replacement servo at our pull-a-part. About 20-ish miles one way. As I took the exit, the trans downshifted after coming out of OD & exhibited some other erratic shifting.

After getting a servo, we checked the KOEO codes while on the lot before leaving.

133, expected
334, unusual
452, worrisome

We cleared the codes & I departed. Made the 20+ mile trip back.

When I got back to my shop, I ran KOEO & got 111/111

I then installed the servo & went for a drive. I did not test my cruise capability at that time.

Got back & ran KOER I got 133, 536 & 538.

Now, during the previous week, I had done some repair to the 3rd brake light/bed light housing & harness. In putting the assembly back in, I pinched the stop light hot lead & blew fuse #13 locking up my shifter column . Since the sockets were pretty crusty, I pulled the whole thing, replaced the fuse & covered the hole with tape. The interior of the roof is bone dry. The wiring is not cracked, chaffed or have any exposed conductor.

Question.

Is the 3rd BL being unplugged causing the 536 BOO (open or grounded) code & is the fuse # 13 part of the VSS circuit? I know in some instances on some 9th gen trucks the 3rd brake light can cause issues with an E4OD.

 

No fuse #13 is not part of the VSS circuit.
Fuse #8 goes to the dome light and cargo lamp and if the dome/cargo light circuit blows fuse #8 the PSOM will not work.

Continuous Memory Code 536 indicates a BOO circuit failure. If the BOO input does not cycle after a predetermined number of transitions from 0 mph to a specific speed, the BOO input is assumed to be damaged and Continuous Memory Code 536 is set.

You can also get the 536 if the brake pedal was not depressed and released during the Key On Engine Running (KOER) Self-Test, the BOO signal did not cycle high and low.

The only way the BOO can cause the E4OD issues is if a lamps filaments is shorted from the marker circuit to the BOO circuit or any other source of power feeding the BOO circuit other than the BOO switch.

 

After a few short trips locally with no other codes recorded, I took the truck on a 40 mile interstate round trip into the metro. On the way out, I used the cruise & it functioned normally. On the way home the cruise did not work & as I exited, the trans down shifted from OD to 3rd, then second. On secondary roads the trans was in obvious limp mode w/erratic shifts.

Once home, the ECU gave up 334 again and 542. Inspection does not reveal much. There may be a grain or two of steel on the magnet of VSS. I will drain, clean & install a catch magnet on the differential cover.

Questions: Is 1345 ohms too far outside the 1400 range. Is there a air gap measurement that can be checked? The VSS shell does not appear cracked.

Afterwards I'll test with the replacement servo unplugged, then plugged unless there is another recommendation.

 

I would think that would be close enough.

MEASURE RABS SENSOR AIR GAP
Remove Rear Axle Differential Cover.

Measure the shortest distance from the RABS sensor pole piece to the teeth on the reservoir bracket (2C250).

Rotate the axle 60°-90°.
Repeat the second and third steps for a total of five measurements.
Are all measurements between 0.127mm (0.005 inch) and 1.14mm (0.045 inch) and within 0.254mm (0.010 inch) of each other?

Yes
GO to «K13».

No, measurements are not between 0.127mm (0.005 inch) and 1.14mm (0.045 inch)
CHECK for foreign material under RABS sensor mounting flange and on carrier housing. REPLACE RABS sensor. GO to «K12».

No, not all measurements are within 0.254mm (0.010 inch) of each other
REPLACE anti-lock ring -- GO to «Pinpoint Test S» to VERIFY concern is resolved.

 

Thank you. Will see what works out.

(On edit: started at top & re-read today. Did not realize air-gap procedure was previously listed 12-26-10.)

 

Drained dif this PM. I improvised measuring the gap & tone ring by using a small ball of plumbers putty on the tip of the VSS. After installation & removal the compressed putty was halved & measured. The depth showed at least 1.MM in several places

I then took a stiff wire & used a cover bolt to position the point less than 1 MM above the exciter/anti lock ring and rotated it through several rotations forward & back. No eccentric/out of round condition was noted.

 

Trying to clean up some threads:

Picked up a used Ford VSS at the yard & it measured 1385 Ohms. Noticed nearly half of the units I looked at were damaged by excessive play in the differential.

Got less than 50 miles or so when the truck set another VSS code, so I decided to drop in the used 6 cyl PSOM I have. I've gotten a couple hundred miles so far & no code. The 2 units I have are almost identical.



Mfg 8-12-93

No sign of leakage or board damage.



Mfg 1-8-94

Interestingly I ran across this thread not long ago which I'll link to since the info might help someone else:

https://www.ford-trucks.com/forums/1...4od-trans.html

What chip holds the mileage? Not sure I can source someone who has equipment to transfer the data electronically.