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Throttle position sensor part # and source?

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Washington D.C.
Thread starter #1
I am swapping a new 700r4 back into my '85 K20 diesel Suburban. Mine came factory with the towing package, 4.10s, and a 700r4, and this is an odd combo because even the big parts stores and nationwide transmission shops tell me that you couldn't get a 700r4 with the 3/4 ton diesel. My glove box option sheet says different.

When I bought the Suburban the 700r4 was shot so I swapped in a nv4500, which was also shot, then a good th400. Over the years my TPS for the 700r4 lockup went missing so does anyone know a part # or a source for the the TPS? I am going with factory wiring so a toggle switch or other aftermarket setup doesn't interest me.
 

THEFERMANATOR

FRANKENBURBAN
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Staff #2
As far as I know, lockup on the early 700r4's didn't require a tps. They were a pretty crude system that locked up at speed, and the throttle cable would cause it to kick down and out of lockup. As old as it is, you would be better off installing one of the many aftermarket lockup kits to control lockup than to try and make the oem stuff work again. And not many 700r4's made it behind the 6.2l. They just weren't up to holding any kind of torque. For what you will spend trying to get a 700r4 to hold up, you could buy a used 4l80e and stand alone controller, and never worry about your trans holding up.
 

Will L.

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#4
Wow 85 with 6.2/700r4? They did it earlier but ate so many under warranty that I am amazed they let any go that way by 85 in a K and tow package to boot.

I am with Thefermanator, dont buy a 700, get the 4l80/85/90.
If you are heart set on it, make sure the supplier has an impeccable warranty and make friends with them from day 1.

On the tps, what pump? 1985 there wasn’t db4 yet but there was the ultra rare db0 pump- and with your combo, maybe it is on there. If it is a db2 pump then then there is plenty of support.
There is a metal label on the ip that will have the number. Take and post pictures if you cant see it.

The db2 tps will not work on a db0 pump. If it is a db0 pump in working condition, you may want to sell it and buy a new pump and pocket the extra $2,000 left over. Haha
 
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Washington D.C.
Thread starter #5
I grew up with an ‘82K5 diesel that had 400k on the original drivetrain when my parents sold it, so they will hold upnif treated right.

I went with the ‘85 because I want an electronic free powertrain. If the lockup doesnt work I can still drive it vs. a 4l80e not working at all. Its my bugout vehicle!

The TPS on these is on the pump, the DB2 and after finding the end of google it looks like the part is discontinued.
 

WarWagon

Well it hits on 7 of 8...
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#6
Is it really an electronic TPS on a bug out vehicle? :facepalm: IMO it's a switch. If I recall correctly there is a vacuum switch on the IP, but, that may be for emissions: EPR and EGR. The emissions exempt military surplus 6.2's out of blazers I got had vac switches on them and I assume they were for the transmission.

Is this close to what you are looking for?

https://www.rockauto.com/en/catalog...uel+&+air,throttle+position+sensor+(tps),5136
 

Will L.

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#7
Ok, there are a couple different tps that can be used on db2. The most common is one I replaced recently on a neigbors pickup, also an 85. We bought it at advanced auto parts made by bwd ec3003. (Had to go look in trash bucket in my garage). I am not 100% that is yours but most likely. Make sure you adjust it properly, dont just screw it down.

There are pump builders all around, you can still buy brand new pumps and tps multiple locations- they shouldn’t be going anywhere- Still same old pricing and made by multiple manufacturers. We got his there cuz he had to pick up his kid that works there anyways and his discount made it $100 and was instock. I Agree with above as to not needing it for that trans. But if you want it...

And as for 4l80e not being good as bug out vehicle- remember all hmmwvs went from th400 to the 4l80e and still emp is not a concearn. They never went 700r4 for a reason. Heck do a manual valve body 4l80 if you feel the need.

A lot of nonsense about emp and avoiding electronic transmission out there. The pulse wave energy it takes to wipe out the control circuits of the trans will melt all your glow wires first, kill any living thing second, then wipe out starters and alternators next by order of energy. The tps beingone of the easier to be damaged parts by the emp since the important stuff for the trans is sealed in an all metal enclosure of transmission (faraday cage) and the tcm to control it is also in an all metal enclosure. Tps is plastic so...
You are far more likely to have 700r4 fail under applied torque than electrical fault stop you.

If still planning on emp contingents, keep spare battery, alternator, starter, and complete harness in a sealed metal enclosure. I have a friend that bought a shipping container to store a rig and gear in to account for emp and theft. Container took very little modification to cover the door seals in metal. Just A hair farther than I go...
 
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Thread starter #8
The emp thing isn’t a big concern its the simplicity of the engine and trans I like. The J code with the 700r4 is rare but the switch looks like the one above, there are just different voltage limits between part numbers.

I’ve been to Iraq 3 times and Afghanistan twice and I wouldn’t call the 4l80e a great transmission.
 

Will L.

Well-Known Member
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#9
Ok cool, as long as you didn’t get drawn in on the emp nonsense that is floating out there was my concern.

On the simplicity side I agree. I wish they made a non electric 6 speed auto like a th400 that just had more gears on top end. Like .40 final drive- haha.
 

WarWagon

Well it hits on 7 of 8...
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#11
The emp thing isn’t a big concern its the simplicity of the engine and trans I like. The J code with the 700r4 is rare but the switch looks like the one above, there are just different voltage limits between part numbers.

I’ve been to Iraq 3 times and Afghanistan twice and I wouldn’t call the 4l80e a great transmission.
In context with a lube modded NV-5600 manual, 13 speed Eaton, Power sucking Allison I would agree: Not great.

For your use I would suggest going back to a manual even though the NV-4500 weak point was the add on OD unit. Better manual trans units out there, but, cost performance the easy button to install is a fresh (rebuilt) NV-4500.

4L80E has a couple weak points being the TC clutch and a manual 3rd overrun lockup clutch. However I get 50,000 miles out of them vs. 1 week (550 miles) out of a 4L70E biased on the POS 700R4 (aka upgraded form of a 4L60E). With the 6500 RPM redline Corvette LS2 in front of the 4L70E a failure of a sprag clutch turns the 4L70E into a bomb as the input drum explodes at 13,000 RPM going through the trans case like butter. (Said sprag failure mode doubles the input RPM to the drum.) So the 4L80E may not be a great transmission, but, it's reliability is light years ahead of the in context comparison POS you are attempting to stuff back into the K20. Point of Fact: the aftermarket has come up with a way to stuff the 1999MY+ 4L80E's in place of the 4L70E bomb on Super Sport Trailblazers because even built 4L70E's couldn't take it. Seriously when you have to consider running a Kevlar blanket or a scatter shield because of the trans design... Mis-adjust the cable and you can smoke that trans in as little as 100 miles.
 

THEFERMANATOR

FRANKENBURBAN
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Staff #14
That TPS listed says for manual trans. It's for controlling EGR and such. 700R4's don't need it. The only electric part is lockup, the rest is all hydraulic. The vacuum switch was for the th-400 as it shifted via a vacuum modulator. Without it line pressure stays in idle mode and it will short shift. You're looking for something you don't need as the TV cable does everything for a 700r4, and governor setup and valve body calibration via the throttle control valve controls shifts, downshifts, 4th gear, and lockup.
 
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Location
Washington D.C.
Thread starter #15
No the tps on the 700r4 controls the converter lockup. There are a few versions that look the same but do different jobs. The California emissions version controlled the efr on the C motors on manual and automatics. Im looking for the lockup tps for the 700r4 on the J code engine.
 
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alaska
#16
IIRC on our 84 there was an electrical circut that controlled the lockup. Went thru several things with the 4x4 light being one of them. There was a ground under the dash disconnected on ours I finally found on ours. Don't remember what the trigger source was but it didn't have a TPS.
 
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Location
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Thread starter #17
Yes sir that is it. I have the factory service manual but unfortunately it doesn't include any part numbers. Plus there aren't any junkyards with square bodies within 100 miles of me.
 
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Thread starter #20
Here you go, even in the shop manual the wiring diagrams say the LL4 engine doesn't use this, but in the 700r4 section it shows the process to adjust it. This must have been an odd ball or mid production change.
 

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