Jump to content

95 D21 Automatic, O/D doesnt work


Recommended Posts

Any one out there have any issues with their Overdrive not functioning. I just got my 95 up and running but it has no over drive and is sucking fuel like crazy on the freeways. Any idea what part may need replaced?

Link to comment
Share on other sites

There's an overdrive lockout button on the shifter. Make sure that's not on. This should also light up "O/D Off" on the dash, which you probably would've noticed by now, unless the bulb is burned out.

 

If it's not that, watch the light in the power mode switch for the trans after you start the truck. If it's flashing, the computer thinks something is wrong. The service manual has a procedure to decode what the TCU's unhappy about. (Should be in the AT section.)

Link to comment
Share on other sites

Does it have issues starting in Park or Neutral? Mine had an issue with the range sensor (neutral safety switch) and the truck always thought it was in park, and would only shift up to 3rd as well.

Link to comment
Share on other sites

I've seen the O/D off light and shes not flashing on the power mode switch. And she has no issues starting in park or neutral. She has sat for the last almost 10 years though so I'm not sure if all the kinks are worked out yet.

Link to comment
Share on other sites

I had basically the same problem you have. I recommend running the codes and seeing what the ECU brings back. User Terranovation posted a very thorough walk through on how to check the codes here. I can't remember which code my Pathy brought back, but it was some sort of solenoid that wasn't engaging correctly. Unfortunately I ignored it, and after 60 miles of continuous highway driving the transmission gave up all together so I got a manufactured one. I doubt the solenoid alone was at fault for the tranny failure, but it probably provoked it.

 

Good luck!

Link to comment
Share on other sites

Its probably a wiring issue - mice. The trans harness connectors are in a bundle on the pass side fenderwell. The wires for the od solenoid can be found there. Sometimes that harness can chaff on the trans under the body. Inspect that, if its good then it could be a bad od solenoid. The switch on the shifter might also be bad. Hope youre good at electrical troubleshooting, good luck.

Link to comment
Share on other sites

I believe the od solenoid is on the lower left part of this pic, might be the tcc solenoid also, not 100% sure. I just overhauled this one a couple weeks ago. My brain is still sore from it lol. This one had lost reverse. Had a worn stator and reverse drum. Had the replace the pump and the reverse drum.

 

6_CCDBB9_C-5_A3_F-4_B8_F-8_E89-_A92679_A

Link to comment
Share on other sites

so the ecu isnt bringing back a code. I push in the o/d button and it revs my rpms up by around 250 rpm. so if im doing 65 on the freeway at 3500 rpm and i kick in od it goes up to 3750 and its also causing mine to overheat. Im almost scared to take it on the freeway because im afraid of blowing the motor out of it

Link to comment
Share on other sites

so the ecu isnt bringing back a code. I push in the o/d button and it revs my rpms up by around 250 rpm. so if im doing 65 on the freeway at 3500 rpm and i kick in od it goes up to 3750 and its also causing mine to overheat. Im almost scared to take it on the freeway because im afraid of blowing the motor out of it

Now that's bizarre. In my 1992 I sit around 3000 RPM's at 50mph until I engage overdrive, which at that point it shifts into 4th, and then into the extra highway gear. I can then cruise 75mph around 2400-2500rpms.

 

Now I don't have enough knowledge of transmissions to actually provide any proper input here, but that just almost sounds like your transmission was either put back together incorrectly (if it had service done to it), or your rear differential has been swapped. If I remember correctly these machines come with 4.3 ratio with the manual transmission and 4.6 with the automatics.

 

If your rear diff hasn't been touched, then it's safe to say you'll probably be tearing that transmission out because that sounds internal...

Edited by Bobsteriffic
Link to comment
Share on other sites

O/D off locks out overdrive (keeps it in third) but it also changes the operation of the torque converter lockup, which could account for the small change in RPM. This suggests the O/D switch isn't part of why it won't engage O/D the rest of the time.

The overheating is not normal. I climb mountain passes with the O/D off and the only time I've come close to overheating was on a 100°+ day with the aircon on full.

Link to comment
Share on other sites

so i now have a new issue with it. Took off the timing belt to change the water pump and thermostat. Now we cant get the marks on the timing gears and the marks on the back plate of the timing cover to line up with anything we do. She keeps sounding like shes on exhaust stroke every way we adjust it (As in we I mean me and a buddy whos turned wrench for 30 years). We're starting to get frustrated with this issue. Any Ideas guys? Oh and Slartibartfast the thermostat had frozen so i think thats why she was overheating like she was.

Edited by Sbrowning0723
Link to comment
Share on other sites

Makes sense! Hopefully that's all it was.

 

The dimples on the timing cover are a rough estimate at best. Don't trust them. Time from the dimples on the cams and crank. Should be 40 teeth on the belt between the cam sprockets dimples, 43 from the driver's side cam to the crank. Your belt may have reference marks on it already at the right tooth counts. Mine did.

Link to comment
Share on other sites

If you haven't done so, buy a new belt, don't reuse the old one. The new one will have marks on it and make it easier to install. As Slart said, 40 teeth between the cam dimples and 43 between the drivers side cam and the crank dimples.

Link to comment
Share on other sites

So heres the update. Put belt on as said in post got the cams set right. Tried turning her and nothing. Went to buy a compression tester and shes not getting any compression. I'm guessing the piston rings finally went. So now it sits for a while longer again.

Link to comment
Share on other sites

Piston rings don't just go. No compression after timing work sounds like there's still something wrong with the timing, or the timing was too far out when you tried to start it before and the valves hit.

 

Or your new compression tester is junk and something didn't get plugged back in properly. Hopefully it's that.

Link to comment
Share on other sites

The marks on the backplate are guidelines. The cams don't need to line up exactly. Get them close, then make sure you have the correct number of teeth between the dimples. With 1 at TDC.

 

As far as compression, your timing is probably off. If the valves are open even a little in the compression stroke, then you will not get anything. Basically a repeat of what Slarti said.

Link to comment
Share on other sites

We're gonna take the intake off to get to the valves for 2,4,6 so we can time the old girl right. Now my big question is if we line it up at TDC will it automatically be starting Compression cycle or no? Like i've said this is my first time so im trying to wrap my head around all of this. I've also been told that the distributor timing is different from the cam shaft timing.

Edited by Sbrowning0723
Link to comment
Share on other sites

The distributor is geared off the driver's side camshaft. You can turn the housing of the distributor to change ignition timing.

 

It's a four-cycle engine (suck squish burn blow) so the crank turns twice in the time it takes the cams (and distributor) to turn once. The #1 piston hits top dead center on the compression stroke and the exhaust stroke. If you haven't messed with the distributor, you should be able to see that the rotor is pointing either roughly at the contact for the #1 plug lead (compression stroke) or 180° away from it (exhaust stroke).

Also worth noting, the crank pulley doesn't have anything to stop you from clocking it wrong on the balancer. You can install it six different ways, one of which will result in the marks on it lining up with actual TDC. If your ignition timing is making no sense to you, stick something like a dowel down the #1 plug hole, turn the engine by hand to find top dead center, then see if that agrees with your timing marks on the crank pulley. (Orientation of the crank pulley will not change your valve timing, but will confuse you when you go to set your ignition timing.)

Link to comment
Share on other sites

Yes, distributor is ignition timing, camshaft is valve timing. If it is at TDC and the distributor rotor is in the general direction of #1, then you are on the compression stroke.

 

Then, get the cam dimples as close as you can, but don't have to be exact, to the dimples on the backplate. Put on the timing belt and make sure the marks on the timing belt line up with all of the dimples on the cam gears and the crank sproket. Make sure you have the right number of teeth between the dimples, and you should be good to go.

 

Oh, and adjust the tensioner to spec so the belt isn't too loose and slips.

Link to comment
Share on other sites

  • 5 months later...

Been a while since my last post. But got a huge update on the pathy. Finally had some time to strip out a cylinder head. Come to find out... You guessed it bent the intake valves shoved them right into the head. So now I'm going to be pulling the other head and will be replacing both heads. I want to thank everyone who has helped with their input in this. I'm hoping before the new year the old girl will be back on the road!

  • Like 1
Link to comment
Share on other sites

  • 3 weeks later...

So have her rebuilt and had her fired up today. But she was really rough and died as I tried to take her around the front of my shop. Now she just sits and cranks. I'm going to do a pressure test and then see if she's getting spark and fuel and go from there. I'll keep trying to post as I go along. Thanks everyone for the help!

Link to comment
Share on other sites

  • 3 weeks later...

She was empty. She blew the fuse and relays because the wires on the sending unit were bare and touching the metal. Now I've gotta figure out if I've got the drivers side injectors plugged in wrong or not. She's firing correctly on the passenger side but pretty sure she's not on driver side.

Link to comment
Share on other sites

  • 3 weeks later...

She is now running great except for this transmission issue still. Now is the transmission a 4 spd plus o/d or is 4th gear o/d? Plus I've got some pics of the rpms she's doing at highway speeds and I wish I could post them...

  • Like 1
Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share

×
×
  • Create New...