4R44E (newly rebuilt) intermittent electrical problem? (98 Ranger)

OOPS! should say 4R44E, I think.

Six weeks ago, son's Ranger suddenly wouldn't shift past 2nd. Also, speedo went dead, and overdrive light flashing. Took to local tranny shop and got talked into complete rebuild.

Same problem came up on way home from shop. Took it back and a few days later picked it up again. Same problem after 1 day. Took it back and they kept for a week.

They say the trans is perfect. They say they replaced the internal wiring harness. They say they found some bad wires in (maybe different) harness somewhere. Then, they say they fixed some wire behind the radio. Took it home, and it ran fine for 2 weeks around town.

Son went out of town (100 miles) last night, and now he is stuck with it doing same thing again!

Tired of these bozos at trans shop. Thinking of taking them to small claims.

They say trans is fine, and we have a wiring issue. Any suggestions on what to do? Temp fix so he can get home, or permanent fix? Do you think putting in a new computer might help?

Trans shop claims to have replaced sensor on rear end, but I didn't actually check.

1995 and up used electric speedometers
1998 to 2000 used the ABS sensor on the rear axle as the VSS(vehicle speed sensor)

But for speedo and computer that sensor has too many pulses per mile, Fords need 8,000PPM
So they used the GEM(generic electronic module), located behind the radio, to convert the rear axles 20,000ppm to 8,000ppm and then out to speedometer and computer.

GEM also runs all cab electrics, wipers, lights, door locks, ect........

If VSS fails then ABS Light would also come on when speedometer went off, because neither is getting PPM signal, ABS gets it directly, Speedometer gets it after GEM converts it.

You should have the OBD Code P0500--no speed signal
And if you have no ABS light then signal is either not making it to GEM or GEM is not sending it out to computer(P0500) and speedometer
If you have no issues with cab interior lights or wipers or any cab electrics then GEM is probably OK, and it is strictly a wiring issue.
And best guess would be the spliced wires coming from VSS wires to GEM

As far as not shifting to 3rd, that shouldn't happen even with no speed signal.
The computer software that runs the shift solenoids will go into Safe Mode or Limp Mode, same things, lol, which will make for harsher shifts, but transmission should still shift even into OD in most cases.
Automatics had pressure shift points prior to solenoids being added, and they still have them, the solenoids just made shifting smoother and more efficient because computer also has engine load data along with driver input like throttle positions, so better MPG and reaction.

Have him unhook one cable from the battery and wait 5 minutes, then hook it back up.
That will reset safe mode, but it will come back if there is no speed signal, but as said I would expect transmission to shift to all gears just do it with more of a bang not smooth, and that is actually better for the transmission, no slipping in Safe Mode, lol.
Also try starting out in 1st then manually shifting to 2nd and then manually shift to 3rd, computer may react better if it knows Driver is selecting the gears

Thanks. Now we are getting somewhere. I'm still confused, but maybe these observation will help. Keep in mind that it is an intermittent problem, so difficult to "test" in controlled environment.

My boy did get home safe. Truck went back to normal after a few hours. Did try disconnecting battery, but that did not help. Might not have waited 5 minutes though.

He did notice that the interior lights were not working when the trans was messing-up. He does not recall seeing the ABS light on. Now that trans is working, so are lights.

Does this help pinpoint the problem? Try replacing the GEM?

Manual shifting does not work (2-3).

So - maybe I understand. Speed sensor is OK because no ABS light. SS also feeds GEM. GEM sends speed data to speedo and to transmission. Speedo reads zero due to no signal. Trans thinks vehicle is moving slow (or not at all), so doesn't shift.

"Coincidence" of interior lights and speedo/trans problems points to GEM. Bingo?

Just ordered a used one of same number from eBay for $20.

Well, got a used GEM. Waited until trans acted-up and swapped it out. No change. What next?

Anyone have a wiring diagram for this? Do the wires for trans and speedo run in parallel, or sequentially? GEM-->speedo-->trans? or trans<--GEM-->speedo?

What color wires would I be looking for?

Should have asked you if you have 4 wheel ABS or just Rear ABS

RABS uses the GEM to convert to true speed
4WABS uses 4WABS Module to convert to true speed

The true speed signal will be on a Grey/Black stripe wire, on GEM it will be Pin 1 on one of the connectors.
From 4WABS module it will be pin 10, same color wire is used thru out.
It is spliced from the VSS OUT of GEM, or 4WABS, and goes to speedo, computer and cruise, listed as S139, splice 139

All are Grey/Black stripe wires

But there are other issues if it still isn't shifting.
An electrical fault could do it, and the fault could also be cutting power to GEM, so no lights.

And just confirm the ABS light does come on when there is the Key ON bulb test

Thanks. Truck is at Trans shop that did the rebuild right now, but I am not expecting them to actually fix it. See comments in RED below

RonD said:

Should have asked you if you have 4 wheel ABS or just Rear ABS Don't know. Truck not here now - how to tell?

RABS uses the GEM to convert to true speed
4WABS uses 4WABS Module to convert to true speed

The true speed signal will be on a Grey/Black stripe wire, on GEM it will be Pin 1 on one of the connectors. Only 1 connector
From 4WABS module it will be pin 10, same color wire is used thru out.
It is spliced from the VSS OUT of GEM, or 4WABS, and goes to speedo, computer and cruise, listed as S139, splice 139 So, if speedo stops, and Cruise light flashes when trans stops working, then problem is before (or in) the GEM, but not after - correct? Or, maybe I should look for and check this splice?

All are Grey/Black stripe wires

But there are other issues if it still isn't shifting.
An electrical fault could do it, and the fault could also be cutting power to GEM, so no lights. only noticed interior dome light not working. Others work, but maybe not checked "all".

And just confirm the ABS light does come on when there is the Key ON bulb test Good point, but truck not here now, so I can't check until it comes back.

Click to expand...

I suppose the new junkyard GEM could also be bad (just my luck).

About power to GEM: Which wire is that? Should it have 12V? That seems easy to check, or I could check them all. Check at GEM plug with it unplugged?

Open the hood, look next to brake master cylinder, fender side, there will be a large unit with 5 brake lines, 2 in and 3 out
Picture here of 4WABS: https://www.ranger-forums.com/suspension-tech-36/4-wheel-abs-2-wheel-abs-119801/
If you don't see this then it has RABS

If there is a working ABS light but it does not come on when speedo is off then rear axle sensor and wire to ABS module is OK

I uploaded the 1998 GEM wiring in this thread: http://www.therangerstation.com/forums/showthread.php?t=162915

You can download them and then look at the fuses it uses

Fuses that say "Hot in run, start or acc" means that 12v will come from the ignition switch under the steering column, then go to that fuse and then out to GEM.
So a faulty ignition switch can cause intermittent electrical issues.

Ignition switch is a Slider switch, when key is rotated a push rod Slides the switch into its 4 positions, acc, off, run, start

Thanks. Truck is still at trans shop. They claim to be "working on it", but I am skeptical.

Well... Truck still at the shop. They said they replaced some "iffy" wires under the hood. Apparently, that did not help.

Now, they tell me they are waiting for a "sensor". Said it receives signal from the computer and send to transmission. Said it is not the GEM that I already tried swapping. Said they tested the sensor and output voltage was low.

Does this sound legitimate? Asked the guy on phone what it is called, but he acted like he didn't know ("my tech is out to lunch").

They have had truck for 12 days now, and we won't get it until Tuesday (4 days from now).

Most sensors are sent a "known" voltage from the computer, like 5volts, called a Reference Voltage, then the sensor sends back a lower voltage to indicate the "state" of whatever it is monitoring.
Like ECT sensor will get 5v and send back 3v if engine is cold, then the 3v will slowly drop as sensor warms up with the engine, at under 1volt engine is warmed up
TPS, MAF, IAT sensors all use that 5v reference

Other sensors generate there own voltage, AC Volts, like crank or cam sensors and Speed or ABS sensors, the spinning of a tone ring near the sensor causes a Variable Reluctance sensor to generate a Pulse signal which can be read with volt meter set to AC Volts, computer just uses the Pulse Frequency, not the voltage

O2 sensors also generate their own voltage by a chemical reaction, .1-.9volts so not much, and an 02 sensor needs to be above 650degF to generate voltage, for chemical reaction to take place

Thanks Ron. What I was asking, actually - is there actually another sensor that could cause the problems described, or are they just blowing smoke?

I'm going to be pissed if it just the speed sensor on the rear end, because they said they replaced that at the very beginning.

If there is another sensor that could cause these same problems, I'm wondering why it took them so long to check that.

I have a funny feeling that this problem will never get fixed.

Well, now I am pretty sure they are just dicking me around. Called today and he said they were "checking the wiring harness under the dash". I asked about the sensor, and he said they tried that last week and it didn't work. When I said he told me Friday that it wasn't coming until Tuesday, he said "oh, we found one on Friday after we talked"! That was at 3PM on Friday.

I asked where this imaginary sensor was, and he said on the firewall behind the engine.

Pretty sure I will be filing in small claims court soon. They have now had the truck for 15 days (not including the numerous previous visits).

Yes, it reads like they have put it on the back burner since, to them, it is a "freebe" at this point.
So they "look at it" when they have no "paying work"

At most shops the "front guy" that takes the phone calls isn't a pro-mechanic, and so any technical details about a vehicle he passes on should be dismissed as second hand information at best and out-right lies at worst.

You may have to bite the bullet and take it to another shop and pay them to diagnose and fix the problem, THEN you can take the other shop to small claims and get refunded for the cost to fix it.
If you have had to rent a vehicle for the 15 days or part of that time then you can claim that as well, and I think that is the only way to get "loss of use", it must have cost you actual $ for courts to compensate you

Well, I feel better about the shop now. It seems that they really were trying to fix it, and did spend some time. I stopped by and they actually had it up front and had the stereo out to access the dash wiring.

Said they bypassed some wiring instead of they to chase bad connections. The phone guy (manager) was actually doing some of the work -had wiring diagrams etc.

He said that somebody had re-wired the cruise control at some point, and those connections looked iffy, and found as rusty ground nearby. Said cruise control is tied to ABS, and obviously to vehicle speed, so perhaps that was it! Note: cruise control has never worked since we get vehicle.

Apparently, they did extensive test drives (gas tank was empty). They feel satisfied it is fixed.

Picked up truck last night, and my boy said he thinks it is shifting better than it ever has.

Fingers crossed, but not optimistic.