93 3500 4x4 4L80E no Speedo or 4th gear

[Gurp]

I picked up a beater 3500 6.5 to use as a work truck. With plans to use it to haul a car trailer.
Need that 4th gear for that. Due to some issues with my 99 1500 the 93 has become my daily for now.

I've replaced the input/output sensors on the trans. Cleaned the VSS. It didn't seat and it was starting to rain I pulled it around front that day and it wouldn't shift out of 1st. Next day reseated it and got 2/3 back. That lead me to believe the wording for the VSS was good.( I could be wrong)
Ordered and I stalled a DRAC/VSSB. No Speedo or 4th gear yet.
The only thing it did do was smooth out the 1/2 shift that was a little rough.

Was reading about the 3rd brake light affecting Cruise Control and TCC on here. Could/would that effect 4th gear and Speedo as well?
I have one brake/tail light completely out. Guy said a bull ran into the truck. He was a cattle farmer had the truck for 10 years or so.

Any good ideas where to look?

 

[dbrannon79]

I am assuming that this truck is a db2 setup? check the TPS operation. this will effect shifting. as for the speedo not working, make sure that the two speed sensors on the tranny don't have the connectors swapped. and check for power to the cluster. if you have a way to check codes it might help. I think that the only way on the db2 trucks is you have to use a GM tech 2.

@THEFERMANATOR can tell you all about how to diagnose these as he is the most knowlageable guy here for transmissions.

 

[Gurp]

Yes it's a DB2 setup. How would I check TPS operation?
Was reading people having the same issue and it being a coolant temp sensor. Made me thing I feel my truck runs a bit cool going to look on my drive to work tonight and post.

 

[Will L.]

Engine off, key on.
Volt meter negative to battery negative, positive to the blue wire on tps.
Throttle at idle position 0.5 volts.
Throttle at full open 4.5 volts.
When moving throttle it should be a smooth increase/ decrease (no jumping around).

 

[Gurp]

I'll be doing this tomorrow at some point.

 

[Gurp]

Temp reading about 160ish it never really goes much over this.

 

[MrMarty51]

A infrared thermometer and temp at the thermostat housing to see what it really is.
Yup, if engine is getting to only 160 ish then it is not warm enough to engage fourth or TCC.
The temp probe for the gauge is located at the front of the left side cylinder head. The temp probe in the T-Stat housing is for the ECM.
Most likely it might need a thermostat, some require two. Try to find the T Stats in Delco brand.

 

[dbrannon79]

that's about what mine runs, maybe a little higher. what degree thermostat are you running? I run a 180.

 

[MrMarty51]

Oh yeah. If the coolant is drained down far enough to change T-Stat, drain it a little farther. Remove right side inner fender well, go to the back of the Right side chlinder head. Remove that plug into the coolant passage. Install a temp probe for a temperature gauge.
Then You have another reliable source for coolant temp.

 

[dbrannon79]

Marty is right, I keep forgetting about the minimum temp for the TCC. in colder weather mine does take a gooood while to get up to temp. drove home from work this evening with outside temps down to near 40's my temp gauge didn't get up the the normal 180 mark in the 6 miles I drive.

 

[dbrannon79]

I think AC Delco makes a 190 deg t-stat for our rigs. not too hot but not too cold

 

[Gurp]

Not sure what T stay is in it. It's in the teens today. I drove it in the 50s and it never seems to get over where it's at now. I'll look into a coolant temp sensor and a new T stat. @MrMarty51 what is the min temp?
I was looking at the 190 fro. o'reilly's today actually.

 

[Will L.]

Need to find a different location for the aftermarket temp gauge (which is a good idea). On db2 engines that location has a temperature switch with 2 wires that control the cold start circuit. On the top of the rear, still the right side head (same place where the thermostat crossover would come from on the front) there is a block off plate. Kind of behind the ffm. Look to see if you have one that is a threaded unit or flat block off plate.

If you are good at welding, just remove it, drill a hole, weld on a 1/2npt coupling and your good. Otherwise buy one of the type with the threaded hole in it.

Just clean the two surfaces and use a little permatex ‘the right stuff’ to reinstall.

Also, if lease fill out your signature line with truck details. We all do that so as we read each new post we can see what is correct for your rig. Also include modifications made.
Mine is not a good example, look at the other 2guys.

Post pictures of your engine: helps us see if anything is wring, and what type thermostat crossover you have- there are some people that make the mistake of replacing a broken one with the old hummer/ hmmwv crossover and things go bad from there. Please select the “full image” when you post them.

The 2 pics below, one is a solid block off plate used most common. The other is one someone drilled and tapped, but too small of hole for what you need. I can’t find pics of the factory block off plate with 1/2” hole- if anyone can post a pic that might help him.

 

[MrMarty51]

I run 195 T Stats in my 6.5. Many others say a 190 or even cooler. Whichever T stat You use, if it were mine, I would not go below a 190.
If the cooling system is all in good order there should be no problem going with the 195 stats.
My truck, the new Kennedy Diesel fan clutch was not engaging and causing my engine to run a lot warmer than I liked. 210 on a day that the temps was in the 110+ range. Just way too hot for engine temps.
After @Will L gave me the suggestion to drill a self drilling sheet metal screw through the fan clutch then take another run, that stopped the over heating issue. The temps that day for the test run was over 112 degrees so I am thoroughly convinced that the heating issue with my truck is thoroughly cured. The temp on that run did not go above 200 degrees.
I will be installing the electro viscous fan and clutch kit that @AK Dieseldriver had researched and is running on his truck. That is a mighty nice system.

 

[Will L.]

@MrMarty51 you have to give folks the disclaimer that running the screw through the fan clutch is a permanent alteration, just removing the screw doesn’t let it go back to normal.

I believe Gurp should have a single thermostat block off style. Yes a 190/ 195 AC Delco stat would be what I would install for checking this. Need the pic of the crossover to ensure what is needed. Since the truck was recently bought and is basically 30 years old at this point- chances someone replaced the original is high enough to warrant verification.

 

[dbrannon79]

@Gurp if you end up getting a replacement tstat or any other parts for that matter, ALWAYS use GM ACDelco when available and when funds allow. trust me I have learned the hard way! I should have listened to these guys here but I was hard headed. on my tstat, I have replaced it like three times in the past two years I have owned my rig. the auto parts usually sell Stant brand. each time I opened up the cooling system for various things like heater hoses, flushing and such, after a refill of coolant my tstat always started acting up.

I don't even like the stats that have that little bleeder thingy on them because it allows coolant to bypass the stat and take longer to warm up in the winter especially with a higher output water pump.

a suggestion for you if and when you open your cooling system is to do a complete flush on the engine block, radiator, and the coolant bottle. when I flushed mine, I didn't get very much gunk from the engine or radiator but when I pulled the coolant bottle off the firewall, it had gobbs of rusty nasty crap that was thick like mud inside it.

 

[Gurp]

Checked temp after driving 8 miles and was reading same spot as last pic. Ordered a delco 195 stat and a coolant temp sensor

 

[dbrannon79]

Yep, sounds like a thermostat is a good move. looking at those temps I would think that ether the current one might be stuck open.

with those temps you will see shifting issues where the trans might not want to allow TCC lockup and possibly 4th gear. iirc the minimum temp for this to work correctly is 160+. others will chime in that know more than I do.

 

[Stoney]

does anyone know the actual temp you have to achieve for shifting and tcc?
Word of advice don't get the 175 tstats...I bought them cause I was doing alot of hauling and ran hot all the time....there crap.. putting 190 delcos in it...

 

[dbrannon79]

@Stoney I believe I remember Will or Ferm saying it has to be around 160-165 or so for the TCC to lockup.