hi all....

Sorry if this may be long, but I want to explain the events which led up to the issue. The truck is a 1992 bronco custom (ex police), 302, E4OD. The truck has been exceptionally maintained and has been nearly perfect the last 4 years I have owned it. Tranny was rebuilt 2 years ago and has been perfect as well until recently.

The problem started 3 weeks ago when driving, the engine just quit with no spark. diagnosed everything as much I could with a multi-meter, pointed to the pcm so I put it in the shop since it was beyond my tools/skill. electric shop replaced the EECIV computer and got it running. claimed there was a short but wouldnt tell me exactly where it was??? I could also not see anything done to any harness, so I suspect they lied. Figure I got screwed there. when I got it back, the transmission was now messed up. It will drive in 1st, 2nd and reverse, but no 3rd or OD (it feels like it is just slipping badly, barely moves). Oddities I noticed are the OD light on the shift lever flashes on-off and the 4wheel low dash light flickers and gets brighter as I rev the engine. The 4-low dash light eventually goes off. Also, the electrical shop gave me the new EEC-IV computer with the check-engine light on and would not tell me the codes. The check-engine light is on constantly. As of monday, I brought it to a trans shop and they tell me that the 'solenoid pack' is no good and the tranny needs a complete rebuild as well Since the trans was perfect, I think they are not being straight with me as well so I am picking it up as it was (or atleast I hope).

I can do anything it needs mechnaically and electrically that can be done with a multi-meter. problem is that I am just not sure where to start and I also see that electrical component issues with these trannys seem to be plentiful.

now the questions....

has anyone had this same issue or know the component that would cause these issues?

I am going to work on this myself from here out, so what would be a course of diagnosing the issue? I can test or replace most any part, but what would be the best course of things to try (or replace) to help get to the problem?

Is diagnostics info available for testing tranny electrical components?

Is the solenoid pack replaceable from the pan without getting into the tranny? anyone know a good place to buy a replacement pack if needed?

I have driven it a bit (<20 mi total) with the issue, but only in 2nd which seems to work fine. would this trash the tranny mechanically? I never went above 30mph, just to work in very slow traffic.

where is the PCM located?

the EEC-IV computer was from a 94 model, could this be it or are there any differences I should be aware of?

well, any help, guidance or info would be GREATLY appreciated. the tranny shop wants $1600+ to replace the pack and rebuild the tranny which seems crazy since it was working perfect previously. It may need it still, but only as the last thing if I can prevent it.

TIA,

Bill

 

The first "shop" must have really screwed it up! I don't know why you are not taking it back there and making them fix their mistake, whatever it was they did wrong.

But if your set on trying to fix it yourself, I can make some recommendations. But it's not going to be some quick fix or replace this part and your good to go. I have no idea what is wrong. Anyway...

Spend some time looking at dalidesign.com, you can find a drawing on how to trigger and receive EEC-IV trouble codes. There are also 2-digit and 3-digit trouble code lists there for free. In the 3-digit list, there are trans fault codes up in the 400-500-600's fault code ranges.

Acquire a Bronco/F-Series EVTM for 1992. If you can't find a '92 anywhere, a '93 will be better than a '91. EVTM is the official Electrical Vacuum Troubleshooting Manual printed by helminc.com, can find them on ebay sometimes. It has the wiring and electrical systems broken up on a functional page basis. Much better than trying to mess with one of those poor inadequate Haynes or whatever manuals. I figure you are going to be doing a lot of testing and measuring, and tracing, and need accurate information.

The PCM is under the dash to the left of the drivers knee. Look under the hood, between the brake booster and the fender, and look down. The PCM's underhood side of the connector is on the firewall there. That will give you an idea of where inside the cab to look for it.

I wonder if the proper solenoids are being powered to get to 3rd or OD. But that would be getting ahead of the game!

Just some thoughts.

 

Sounds to me like they put the wrong PCM in there, and since the tranny is controlled by it also, it isn't working correctly. Any junkyards around that you can get a computer from? Now you are gonna have to get the same year/engine/tranny PCM, because you don't have the old to compare. MAKE THE FIRST SHOP PAY FOR WHATEVER YOU DO, BUT DO NOT LET THEM WORK ON YOUR TRUCK!

Good luck, and have fun scouring the yards!

 

The wrong year of computer could screw things up. You can get a code reader and manual for under $20. I do my own diagnosis with that before taking my truck to anyone for repairs.

Jim

 

ok, some more info....I picked up the bronc from the tranny shop this morning and went and got an actron code scanner ($29) to see what the error codes were. I only performed the KOEO test as I was short on time, but here are the results:

(bat disconnected for 30 minutes while changing tps before codes checked)

first set of codes:

638 - trans oil temp - low voltage
553 - thermactor air diverter (not sure what this is)

second set (continuous codes):

157 - mass air flow sensor voltage too low (where is this?)
638 - trans oil temp - low voltage (is replaceable?, how to replace?)
639 - turbine speed sensor- insufficient signal level (this the sensor in the rear axel?)

I replaced the TPS today since I noticed the wires were pretty trashed and was falling apart anyway. after installing the tps, the truck seemed to drive just a bit better in drive, but very shortly drive started slippin again. It also felt like the tranny was starting in 3rd, not first. first & second still seem to work fine.

I am still skeptical about the 94 EEC-IV computer, but I am holding off until I get a firm 'yes, it wont work' instead of it could be... a new one at the auto store isnt cheap ~$200. anyone got a good used one ? I also still have the lit-up 4-low dash light and blinking shifter OD light.

Another thing I would just like to make sure I am clear on is PCM = EEC-IV? I just see both refered to, but nothing saying each is the same.

well, thats where it stands now. any further info provided would be appreciated. if more info is needed, let me know!

Thanks,

Bill

PS. Torky2...thanks for the lead on the EVTM manual...I got one on the way

 

I typed up all sorts of stuff, hit the submit button, and it all was lost!

But, in summary...

I think the first step may be to copy down numbers off the PCM (EEC-IV) box. And then see if it can be matched up as to the specifics of what vehicle specifics it came out of. Like same engine, same trans, Mass Air Flow (MAF) versus Speed Density, 4WD versus 2WD, to name what I can think of at the moment. there were 2 different electronically controlled trans's in '94: the E4OD, and the 4R70W (used to be AOD-E, but with the closer 1st gear ratio).

The wiring, and what connects to what, engine controls, trans connectors and wires, sensors, etc. will make a lot more sense when you get the EVTM. There is a lot of info there. It would be worth looking at the 4WD control too, since you have something weird there that may be a clue.

 

I am pretty sure '92 did NOT have mass air, therefore you should not be getting mass air error codes if you have the correct PCM (Powertrain Control Module) aka EEC-IV. That combined with the "new" transmission problems indicate it is the wrong computer. If you do have mass air the sensor will be between the air filter and the throttle body.

According to http://www.baumannengineering.com/e4odinf.htm a 302 truck would not come with the E40D. However since you have an ex police truck it may have gotten the E40D. Use the above link to verify if unsure.

If you are confident that you have the E40D transmission then the first place you went most likely put in the wrong PCM based on a 'regular' Bronco with a 302. As mentioned above you must match the PCM to the trans type. First go to a local Ford dealer. Bring your VIN. Have them look up the correct replacement computer part number. Now have them look up the replacement part number for a 302/4R70W engine/trans combo. Go back to the place that did the work and get your old computer back. Ask them just exactly which PCM they put in, ie was it for a 302/4R70W or a 302/E40D. Now compare all the part numbers and my guess is that they put in the wrong computer.

Now have them fix their mistake and put the correct computer in. At the very least have them exchange the PCM for a correct one and replace it yourself. It is easy to replace, on a truck in is under the drivers side kick panel, remove the kick panel, then remove one bolt and it slides out.

Good luck.

 

i had the same problem on my 95 f150. checked all over the truck and couldnt figure it out. took it to the dealer. they said it was a short on the wiring harness under the dash. it ended up costing me about $100 total. not bad.

 

Greg,

I cant see how the truck has mass air as I have no flow sensor in the intake, so I am with you wondering why I am getting that code as well. unfortunatly, the original idiot who worked on the truck, gave the computer back on a core charge so I am screwed on the original numbers. The 94 one I got is most likely the culprit with these issues since it ran so well before this and now I get all these error codes? it is definately an A4OD with the big pan so it may be special with a police custom model.

I am going to head to a local dealer and see what info I can get with the VIN. I would imagine that they can get that info from somewhere via the VIN. Once I get the factory EVTM manual, I will know much more as well since I bet it covers all combinations of engine/trans diagnosis info.

Also...mikeindmills...the wiring short you had, did you ever get any info on exactly where it was in the harness and what may have happened? This whole issue started out with a suspected short as well but the first guy was very vague about it. Also, did you have exactly the same symptoms I describe in the first post?

Thanks all,

Bill

 

Just got off the phone with the local dealership....gave me the correct PCM part number based on the VIN:

F2TZ 12A650 ZA

Ford has discontinued this part and so far 2 local parts houses tell me that number doesnt match their systems for a 92 bronco.

Anyone know of a good used parts place that caters to ford trucks and such that could be able to help locating one?

Thanks,

Bill

 

Solved....

I wouldnt take the local dealers word that the factory computer was discontinued and finally dug up an updated part number. A new factory computer from ford fixed the issues and everything is back to working fine.

Thanks for everyones help.

Bill