Trooperthorn

I did not find what I was looking for in the sticky, so I am asking.

Driving the ramchrger in my sig with 1992 ctd mechanicals and wiring on both sides of the firewall, I am not getting overdrive.

1. What all influences the od on the 92s? I know there is the tps, the switch in the dash, the temp sensor on the coolant line. I know I am missing something.

2. Do I understand correctly that if I ground the od solenoid, I will have od all the time? If this is true, I can start there and work my way away from the tranny until I find the culprit.

Any ideas on how to troubleshoot this would help. I am from the school of thought that automatics run on heat and magic.

Thanks.

wannadiesel

Electrical things that will keep you out of OD:
No signal/open circuit from the crank sensor (PCM thinks engine has stopped). If the truck is charging using the regulator in the PCM this is not your problem, should set a code 11.
No signal/inappropriate voltage from the TPS. Should set a code 24.
Open trans fluid temp switch wire or temp switch unplugged (PCM thinks trans is too hot).
Open circuit on the coolant temp sensor circuit (PCM thinks it's too cold for OD). Should set a code 22.
No/erratic VSS signal to the PCM. If the speedo works OK this is unlikely but not impossible, should set a code 15.
Grounded Park/Neutral sense circuit to the PCM due to bad/misadjusted NSS or a pinched/chafed wire (PCM thinks you are in neutral). If the engine will start with the shifter in "D" this is your trouble.
No voltage on the blue wire to the OD solenoid or an open in the ground wire. Should set a code 45. You can ground the solenoid in 3rd gear to check that it (and the OD unit) are functional.

The dash switch is just a momentary pushbutton (NO) that tells the PCM whether or not you'd like OD. The PCM makes the call on whether or not you get OD. The switch is totally unnecessary for OD operation.

So make sure everything I mentioned appears to be plugged in and functional, check your codes (see the sticky for how) to make sure the PCM is happy, and ground the wire that ISN'T blue while rolling in 3rd to make sure you have a working OD unit.

Alwaysworking

i think thats it since he doesn't have the crank senser, or last time i saw it he didn't

Trooperthorn

This is my mystery. The engine/harness is supposed to be a '92 (I never ran the vin and don't have a title), it is intercooled, and has the pcm outboard of the battery in the front of the left fender, but it has no crank sensor and it has a voltage regulator on the firewall. The speedo works fine.

The fluid temp sensor wires look hinky. The plug has been replaced with two small, female spade connectors "glued" together with orange rtv. It is wired in place. Since you say open temp switch may be the problem, I should be able to bypass the sender and connect the two wires together, correct?

In case you have not yet figured this out, This is in my ramcharger in my sig. I tried to make it all factory 1992 ctd. I will bypass the trans temp switch firs then ground the not blue wire next. And get back to you. Thanks guys for your help.

JD730

[QUOTE=Trooperthorn;2152988]This is my mystery. The engine/harness is supposed to be a '92 (I never ran the vin and don't have a title), it is intercooled, and has the pcm outboard of the battery in the front of the left fender, but it has no crank sensor and it has a voltage regulator on the firewall. QUOTE]

What you describe sounds like a late 91.

Trooperthorn

So if it is a late 91, what replaces the crank sensor to tell the pcm that the engine is turning?

wannadiesel

Like Mike said, you have a '91.5 there, not a '92.

The '91.5 PCM runs the OD a bit differently than the '92. There is a coolant temp switch in series with the fluid temp switch, in series with the "override module" in the dash (runs the OD button). Unless the PCM sees ground through this circuit (cavity 10 on the PCM connector), OD will not be engaged. So the coolant temp switch and the trans temp switch need to be plugged in, and you must have continuity across them with everything at operating temperature. If there's a problem with that goofy "override module" that runs the OD button it can be replaced with a simple on/off switch. NSS, TPS, and VSS inputs are the same as the '92 - '93 trucks.

Trooperthorn

Did a little poking around today.

First, I unplugged the trans fluid sensor and connected the two wires. Test drive resulted in still no overdrive.

Next, I tapped into the non-blue (red) wire at the solenoid and brought a wire up to a toggle switch in the cockpit. From the other side of the toggle, I took a wire to ground. On the test drive, I got up to speed and flipped the switch and voila, overdrive.

So, I know the od works. There must be either an open in the mentioned ground circuit or a bad override module or a bad dash switch.

Nybody have a pic or discription of the override module of do I just need to trace the wires back from the switch?

What will happen if I leave the toggle in the closed position. Will the od automatically kick out based on tps/vss info to the pcm? I am thinking of replacing the dash switch and override with a single toggle.

unixcowboy

The pcm uses the same wire you grounded with the switch...It can't remove the ground because you are over-riding it.

IF you feel like chasing wires, I'd start with pulling the OD plug and using the wire you're running to the switch as one side of a multimeter try following the ground wire up into the harness......Bet you got an open wire...

OR you could run a wire from the pcm plug - I believe it's pin 30 - parallel to the harness and connect it to the wire you have running to the switch...

First I'd start by pulling the pcm plug and see if you have continuity from your switch wire to pin 30 - betcha don't..Since you know 'your' wire is good, the open has to be in the harness.


Was I clear as mud ?

wannadiesel

You're going to love this: The OD module is mounted on top of the lower dash brace just to the right of the glove box. So pull the glove box and look to the right and you should see it, it's a little box with 6 wires going to it. Would you ever in your wildest dreams thought it would be clear on the other side of the truck? Once you find the little booger, jump the orange/white wire to ground and go for a ride. If you get normal OD operation, then the module is bad. If not, then trans switch, coolant switch, or harness have a problem. Again, if the problem is the module it (and the dash switch) can be replaced with an ordinary switch.

Again, the dash "switch" is a dummy, it's just an NO momentary pushbutton. The PCM (or in your case the override module) does the actual switching.

If you leave the "mystery switch" you rigged closed you will get a stacked OD shift, that is the trans will immediately shift into OD when 3rd gear applies.

Trooperthorn

Thanks again fellas. I will get back to you again when I check this further. for now, I just ordered my guages and gsk and tailpipe, so, since it sorta works, it just fell on the priority list.

Wanna, just to be clear, if I replace the override/momentary switch, do I just switch the orange/white to ground and ignore the rest?

Trooperthorn

I looked for the override switch today. Couldn't find it. Pulled out the glove box. Not there. Looked under the dash all over. No plugs with an orange/white wire.

Then I found it. It was laying on my shop floor in the harness I did not use.

Apparently, I used the harness out of a 1993 ctd instead of the one out of the 1991.5.

Now I am faced with a dilema. I could make the od work the way it is, but I need the '93 harness for the '93 engine that is going into my crewcab. So, it looks like I will be pulling the dash apart to swap out the harness.

Chime in if you have any other ideas.

wannadiesel

Yeah. Run a wire from pin 10 on the pcm (red/white) to whatever sort of switch you want to mount in place of the original OD switch, then to ground. This will give you automatic OD operation when the switch is closed and lock out OD when the switch is open. This will also bypass the trans temp and coolant temp switches, but they are useless anyway.

thegoat86

Just curious, I am having the same problem as trooperthorn. Do I test by switching the module wires (orange and white) together? or do I switch them with a wire I run to ground? I have a 91.5 w200 with correct wiring harness, so thats not an issue. Just trying to verify before I fry my pcm. thanks.

Rampage1967

I don't remember the colors, but that will get you OD if the module is bad.
BTW., the module is part # 56003275 & it's $49.50 from Chrysler . .
Mine is still jumpered & the dead module is on the desk in front of me.