obd1 location?

[1984potato]

OK, I have searched and found nothing on either the DP site or under the dash of my truck. I went outside, all happy that I bent up a perfectly good paper clip to get codes from "Potato" (the truck really looks like an Ihado baker) and looked for 20 minutes. There's nothing there!

Where do I look to find the port? I have code sheets from the DP and a great picture of the port but it is nowhere to be seen on my truck. There's holes under the dash but no port.

Port, port, port where are you?

Thanks,
Haus.

[JohnC]

You have to have a PCM or ABS or 4L80E or there's nothing to feed data. (so they don't put in the port...)

On my '93 with 5 speed the only thing you could get from the ODB 1 port was ABS data.

[1984potato]

Thank you JohnC!

Oh, so my truck is so "vintage" that I don't have any of that elaborate diagnostic equipment on board. If I had a mechanic in my neighborhood the day I was looking for the port I bet he would get a kick out of me! I looked like a mule getting ready to give up the ghost with my legs up in the air!

Now if I could figure out why my transmission shift points change over night or when I start/re-start during the day all would be right in the world.

Haus.

[HammerWerf]

Potato,

Yep, No Data Port. Gotta use all the mechanic skills you learns. Ain't it great. I've got 2 that way.

HammerWerf

[1984potato]

Mechanical has it's advantages and it's disadvantages. The advantage is no computers, the disadantage is my lack of mechanical knowledge. The tranny is still giving me fits after the rebuild.

Haus.

[DmaxMaverick]

The 1984 ECM was passive on the Diesels. No ABS or "electronic" control for a tranny. It did, however, monitor/control the EGR and may be included in the TCC loop (it is for CA, not sure about fed 84). If it hasn't been removed, the ALDL (Assembly Line Diagnostic Link) should be located under the dash near the steering column and lower trim panel, but may be under the hood on previous models (just not sure). One of the pins in the ALDL is for TCC diagnostic activation/monitoring. If the ECM and/or ALDL has been removed or disconnected, it could activate the check engine lamp, as well as prevent the TCC from locking. The tan/blk wire at the ALDL should be the TCC wire.

Your C1500 truck should have been OEM with a C code engine/emissions system. Changing the engine/components to a J code engine would leave some loose ends with the smog stuff, and foul the ECM.

What, exactly, is your tranny doing/not doing? If it's just a matter of the shift points being off, either your TV cable needs adjustment (most common), or it has the wrong (or defunct) governor in the tranny. A gasser governor will make a Diesel shift "funny". A wrong governor and a poorly adjusted TV cable will shift really bad, and possibly cause serious tranny damage.

[1984potato]

DmaxMaverick,

Glad you chimed in! The majority of the time I drive like a 90 year old man in diapers so the shift points go right along with what everyone on TDP states should happen in normal driving conditions. 1-2 at 15, 2-3 at 25 (seems too soon), 3-4 at about 40, and lock up at 45-50. I have tried the (D) from 1-2 and then mash it to downshift and it does it like Robyn indicates. When I try to drive like a teenager trapped in my old man body that's when it acts up and the shift points go up 10mph on every shift point. It almost seems like something is sticking and not letting it shift right or the transmission doesn't realize the engine is reving so high. I thought about the fuel filter change (signature below) but it just seems too soon. I plan on the change anyway to eliminate it. I thought about the governor (Aamco rebuild from the flatbed truck to their lift) but every time I go back to those guys it costs me $$$ due to some other problem not related to the transmission. How would I know if it's the right parts in the transmission?

Wow, didn't know there was more to the c to j switch. I just pulled off the c intake, plugged the vacuum pods according to the diagram on the radiator support and ran all new vacuum hoses to everything. I had a larger exhaust put in with the balance pipe (TDP suggestion) and started driving. Given the fuel prices going up exponentially, I have not entertained the idea of turning up the pump. Please advise me on what steps I may ahve missed because the MPG is stuck at 25-28 and don't want to mess with that at all. There is no check engine light anywhere on the dash to be seen. I thought I was finished but it sounds like I need to investigate more. It is a Canadian build purchased in Richmond, Virginia in '84, purchased by my old boss a decade ago, and then became mine in June of last year.

VIN: 2GTDC14C0E1507656

I see no ports anywhere. There were two black boxes under the dash that keep falling out onto the long skinny pedal and I have no idea where to look under hood for ports. I guess the troubleshooting guide needs another read through. As always, any suggestions or gentle nudges in the right direction are appreciated.

Haus...

[DmaxMaverick]

I don't think there was an ALDL on 1984 Canadian delivered trucks. That changes a few things.

Your shift characteristics sound normal, or nearly normal. Your geriatric driving habit sounds completely normal. If you drive like a teenager, and it hesitates between shifts, revving too high, I'd suspect a fuel filter right off. Even if you have only 500 miles on it. You can get bad fuel, or even a defunct filter, at any time. Change it. If it doesn't immediately improve, check your fuel delivery. Your fuel lift pump may be on the way out, or you may have a blockage/restriction somewhere. When you put your foot in it, the transmission anticipates a certain amount of engine power at a given pedal input and speed. Lower fuel delivery volume (not necessarily pressure) due to any number of factors will skew this anticipation, and delay shifts. Most typically, it's the filter(s).

I'm not sure what's falling under your dash. Follow the wires, or unplug them and see what doesn't work.

[1984potato]

DmaxMaverick,

Such is life, things just start falling out the older the rig/body gets. I'll try the unplug and watch philosphy on those little black boxes after the filter change this weekend. I'll post my results the middle of next week. In addition, I haven't replaced the fuel return lines yet, they are now on my hit list as is checking the fuel lift pump capacity.

Many thanks,

Haus.

[EWC]

If they are relays , then they are from the buzzer and door chime fuse panel up and to the right of the gas pedal . Does your fuse panel have ECM fuses ? Does the SES light come on when you start the truck .

[1984potato]

EWC,
The black boxes could very well be relays and/or buzzers. They are to the right of the gas pedal, so I think you are dead right.

I have to show my ignorance on terminology. As far as fuses go, I have the new blade type fuse panel in the truck. The only lights that come on are the Wait to start and the parking brake light when it is engaged. I have the WIF light there but the new filter setup doesn't have that sensor yet. I don't see any other places for lights to come on to tell me anything. SES? :confused:

Haus.

[Robyn]

The 700 R4 is an totally hydraulic opperated tranny.
The exception is the Converter lockup which is controled by a TPS switch.
Shift points, firmness and such are all controled by the Throttle pressure valve which is directly effected by the Throttle pressure cable that connects the injector pump to the tranny.

This cable has to be adjusted properly for the tranny to work right.

Here is a quicky test you can do to see if the cable is set right.

With the rig warmed up start off with a very light throttle and let the tranny do a 1-2 shift, just as soon as the tranny shifts, mash the throttle.
The trans should drop back to 1st. If the trans does not drop back to 1 then the throttle pressure cable is set too loose.

The adjustment is at the back of the engine on the rear most cable bracket.

There is a little slide arrangement that has notches in it. The lock mechanism slides side to side under spring tention.
Release the slide and move the cable to the rear in the slide.
Now mash the throttle all the way to the mat and the cable will be set to the proper distance.

If this does not do the trick then there are internal issues with the box.

The 700R can be a booger to get right. If the tech that worked on it was a putz or did not install a good quality shift kit (transgo is my fav over the years) then there can be TP issues.

Its a crap shoot without actually driving the rig and doing pressure tests with a gauge while its working.

Remote diagnostics is a tough call on these.

The 84 does not have any SES lights and such.

The converter clutch has a simple controler that works with the speedo I believe IIRC to lock the clutch at the right speed.
The TPS adds data to the mix too.

Best fix for these is a switch that allows the clutch to be locked out at town speeds and then let it lock up at 50+ ( there are depending on the year and model of the tranny about 17 different wiring and switching setups internally on a 700R with all sorts of gizmo's to do different things depending on the application and if it was Cal or Fed and then it gets complicated to the point of agravation.

As long as you have a 4th clutch switch and a 4-3 downshift switch connected in the setup so 4th has to be closed to energize the TCC and the 4-3 switch will unlock the clutch so the downshift is not brutal your OK.

The constant in out in out in out just trashes the little clutch in the converter.

This clutch is a couple rings of paper lining on a floating disc that is splined to the input shaft and when the pressure is directed behind the disc it locks the shaft to the pump housing (converter case)

The valving depending on the model can be a simple electrical solenoid to a hyadraulic valve and the solenoid and then add the various VB switches to the mix. Oh and dont forget the temp sensor so the clutch wont work when the thing is too cold

These clutches are designed to handle low torque cruising speeds only and will destruct when subjected to a lot of on off stuff and or high torque loading such as use in 2-3 and 4 and compression braking.

Many folks will set them up to run a lower speeds and use the compression braking but the clutch will fail in due time.

I have had a specialty shop rebuild a converter for a 700 and add more clutch material (larger ring)
Its still a bit shakey for constant hard use.

As far as the shifts hanging it could be a governor issue too.

If it only does the hangy thingy when your on the thing hard then the governor amy be (1) the wrong one (2) sticky governor???? (3) wrong springs in the governor.

You can access the governor easily enough. Just pry the little round cover off (back of the tranny LH side, looks like a pregnant front wheel bearing cover)

The governor will slide right out. It has a plastic gear on the end of the stem that mates with the output shaft gear.

You can try replacing the governor with a known good one for a DIESEL
These are different and have a different calibration than one from a gasser 350 or????


The gasser unit will cause the engine to wind up far more before the shift depending on the throttle position.

The C-J thing is a moot point. Same tranny, same calibration on the VB so dont sweat that.

700's are not 700's are not 700's
Governors come in several different flavors depending on the application
There were units for the diesel,the V6 and the V8 and depending on the usage there are even more variables.

Good luck and keep us posted

Robyn

[1984potato]

Ongoing...

DmaxMaverick,
I changed out the fuel filters last night (on order/delivered yesterday). I drove like my usual self last night (grandpa in an old pick up) to get ready for the morning commute. AM showed the same issues with high revs prior to shift and hanging on to the lower gear when traveling "city speed". I ruled out the filter but the return line on the IP still needs testing (where's the time going?).

EWC,
I haven't unplugged any of the boxes yet (too many challenges, not enough day light). I plan on it to see if "stuff" is really necessary.

Robyn,
The truck loves the wide open interstate as evidence by its smooth running and the smile on my face but hates in town.(issues identified here)..sounds like its owner too. The throttle pedal is stiff (as it should be) and you have convinced me that I know nothing about transmissions so the beloved Aamco will get a few more cracks at up selling before the 12 month warranty expires. After the warranty period...may the Lord bless me with a rubber mallet and you with the patience to tell me where to hit the darn thing! So many variables, so little time. THis is actually kind of exciting to think of the possible applications for the 700 variants.

I will address the high rev shift points (governor/springs), hanging shifts when running in town at a set speed, and question the thinking behind the transmission dropping completely out when coasting (engine idles when coasting-totally normal from what I gather).

I'll post up in the next few weeks with my results and I thank each of you for your responses.

Haus.

[1984potato]

Without much fanfare, the truck is running like it was the day it pulled off the show room floor. The boys at Aamco were able to diagnose the high shift points/not shifting at constant speed and replaced the governor. Everyone, including the owner of the shop has spoken to me about this rig. I now drive away politely and quietly :(. My son will miss the high shift points and revving engine soot. He called the black smoke an "Anchor" around turns.

I will start unplugging the boxes under the dash to see if they are needed or not. This truck has every bell and whistle, can't wait to start replacing electrical components and motors next.

Thank you everyone for your input. I'll be back, oh trust me when I threaten this, I will be back!!!:)

Haus.

[1984potato]

Thanks guys for the information. You have helped me get this wonderful machine running great.

Bump.

Haus.