patdaly

That's actually a pretty good pic for the conditions you faced, that being said though, that picture won't tell you anything, the black plastic is just to keep the terminals nice and easy to hook up. Stock, in 1992 the diesels went to Internal PCM regulation, so yours is probably still stock. In the event someone did convert it though, look at the green and blue wires to see if they lead over to the PCM, not sure if the blue is all the way there or goes to the ASD relay, but the green one does for sure. If they haven't been cut into and run to an external ( old Chrysler or Ford style ) relay on the firewall, you are good.

StorminN

Ok folks,

What do you make of these codes? According to the sticky, they should be displayed in numerical order?


Thanks,
-N.

StorminN

Oh, and I just checked... the alternator green and blue wires come about a foot off the alternator and go into a plug, the other end of which disappears into a wiring harness that wraps around under the windshield. I don't see any out-of-place relays or regulators, so should I assume those two wires follow that harness all the way to the PCM under the front left fender?

j_martin

The codes are printed in order. I think they are displayed in the order that they occur.

The PCM is handing you your task on a silver plate. It says that there is a fault in the TPS (probably the voltage setting thing) and that also the OD solenoid doesn't look right, either open or shorted.

Set the TPS like the sticky says....no problem, voltmeter and 10 mm end wrench the only tools needed.

Then troubleshoot the OD solenoid and find either the bad solenoid or more likely a broken or dirty and open connection. The blue wire should be 12V with key on, the other one is the solenoid control, driven to ground by the PCM.

Codes read 12, 45, 24, 55

12 Battery's been disconnected
45 OD Solenoid shorted or open
24 TPS under or over voltage
55 I'm done, goodbye.

Alternator is hooked up or it would throw a
41 Generator field fault

StorminN

So should the TPS voltages be taken at a certain time? Like, after the truck has been running and warmed up, and then soon after it's shut off?

If not, it seems like the grid heaters would affect the accuracy of the voltage readings... if I'm looking for an accuracy in the tenths of volts –*heck, when the grid heaters come on in my truck, the dash gauge goes down 4 volts or more... never mind a couple of tenths...

If this weather lets up, I'll get out there and check it again... over an inch of rain here in the past 14 hours, and windy as heck mixed with it, too...

StorminN

Ok, I caught ten minutes of light rain (it's pouring again now).

The sticky says the "at rest voltage" should be between 0.6 and 1.2 VDC... mine had been 0.233 so I adjusted it up to 0.9 VDC... the adjustment is weird, it seems like the part you put your wrench on has a tendency to spin with the shaft when the throttle is moved. I was trying to adjust to 0.9 V and even just taking my wrench off, the flats part would spin a little (sort of "spring back") and throw off the reading. Is there a set screw or something under the TPS cover that adjusts how tight this is?

Regardless, I got it adjusted so the "at rest voltage" is 0.857 VDC and WOT is 3.356 VDC... that's a gain of 2.499 VDC, which is smack dab within the target of 2.25 to 2.75 that the stickie talks about.

So I took the truck on a test drive and... no difference. I still only seem to have three gears, and when I'm cruising at 50mph and push the "O/D OFF" switch, nothing happens. What speed range would the 3-4 shift normally happen?

By the way, which transmission am I likely to have? The A518? If so, which model?

Thanks,
-N.

bobva

If by chance you dont know.

Dodge autotrans fluid level must be checked in N not Park..

StorminN

I do know this, thanks. I just got this truck back from the tranny shop this week, a fluid change was part of that service... I assume they put in the right amount, but I guess it would't hurt to check again...

-N.

j_martin

The adjustment is just a sheet metal screw jammed into a nylon adapter. Of course you have to hold the linkage steady to adjust it.

You have the A518 transmission, which is basically a three speed hydraulic transmission with an electric overdrive unit on the back. Your PCM is saying something is wrong with the wiring between it and the solenoid, the solenoid's power source, or the solenoid itself. When you shoot that bug out, you'll have a 4 speed.

I am getting a bit tired of repeating myself.

StorminN

Sorry if you feel like you're repeating yourself, I appreciate your patience. I haven't worked on these Dodges before, so it's a little curve to learn the terms (I only learned what "CEL code" and "PCM" meant in the past day), or even figure out what equipment I have – ie., A518 vs. 46RH vs 46Re, what year trucks they each came in, etc. So I've got a A518... got it.

I realize the next step is to figure out if the OD solenoid is getting power, and if so, if it will work. I will test for 12V on the blue wire there. If I get it, I'm trying to figure out if I should wire a jumper directly to the plug on top of the tranny (bypassing the PCM and grounding the solenoid)... it seems like that's the way to do it, and if it works there, then work my way backwards to the PCM and check the wiring between the PCM and the tranny... I read a thread here somewhere... plug into pin 56(?) on the PCM harness, etc.?

The tranny shop said the tranny wiring all looked ok... their opinion was that the valve body has metal / particulate in it and it's sticking, and that's what's preventing the OD from working... but they didn't specifically say they tested the OD solenoid, or the solenoid wiring (though I specifically asked them to check the wiring). I can't tell if they really checked that stuff out, or were just trying to sell me a rebuild...

Thanks,
-N.

maybe368

Nobody is forcing you to post, are they? If so, try 911, because that is some kind of crime I think ...Mark

j_martin

Ignore that guy. He always picks up people's offenses, whether they are offended or not.

I was just surprised that you fixed the TPS and expected a cure after the detailed explanation of your CEL codes and what they mean.

You can check the resistance of the Solenoid. It shouldn't be shorted or open. I don't know exactly the value it should be, but I would guess 3-6 ohms.

Then, if there is 12V available, rig a toggle switch to ground and take it for a ride. It should shift into OD when you ground the solenoid. If it doesn't there is internal transmission trouble. If it does, then troubleshoot the wire between that connector and the PCM. Usually the trouble is just a cruddy connector.

Another thing you could do is rig an indicator lamp between the wires on the connector and see if the PCM and the transmission is working all at once.

I do know that the OD solenoid doesn't like any contamination at all. It isn't very expensive or very hard to replace.

I think you should probably find another transmission shop. Checking OD is standard on these transmissions, and a decent transmission shop should have been able to tell you in short order what is wrong with it.

Around here, I use the NATCO shop in Isanti. The shop's good enough that my son brought his truck over from Montana to have the transmission re-worked.

maybe368

Maybe so, but it seems the you are always the offender. At least "that guy" knows how to be civil...Mark

patdaly

You have it going in the right direction. I don't have a 1993 FSM, but I believe the 91-1/2 is the same, here is the wiring diagram covering the OD.

j_martin

[QUOTE=patdaly;3265170]You have it going in the right direction. I don't have a 1993 FSM, but I believe the 91-1/2 is the same, here is the wiring diagram covering the OD.

/QUOTE]

Not quite. The OD solenoid n the 93 is driven directly by the PCM pin 55.

The ten position connector in the diagram is under the intake manifold near the back of the engine.

The PCM drive is an open collector circuit, so you could suitcase splice into the orange/lg wire and drive it to ground without hurting the PCM. Just be sure it never gets 12v straight to battery or may take the PCM out. (shorted solenoid)