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Need some help with an EZ-TCI TCM with a 6.5 diesel.

dbrannon79

dbrannon79

I'm getting there!
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Hey guys. On the 93 truck I just bought, I have been diagnosing why it shifts hard from 1st to 2nd. I went through all the setting in the programmer and was viewing the live data when I realized that it's not getting an RPM signal.

I traced the wires and see that the RPM module is connected to the tach signal wire on the alternator. This gives no signal, so reading in the TCI instructions, I decided to try connecting the RPM signal wire direct to the tach output on the alternator only to see that the TCU will read 3600 rpm at idle. the book shows that the TCU needs a square wave signal similar to how the negative on a ignition coil gives on a gasser.

looking for options I see this engine still has the factory cam sensor installed but not connected (ESS sensor two wire). Also the factory 93 TCM is in the dash and still powered with the factory harness. I and wondering how this cam sensor works giving signal to the factory TCM wondering if this sensor can be used for an RPM output.

I have been looking but I need some help to find a factory service manual for the 93 diesels or the TCM wire diagrams.
 
Last edited:
The ESS has an 8 tooth reluctor in it, so it gives 4 pulses per crank rev (it's driven off the cam, so it runs at 1/2 crank speed). It's just a regular variable reluctance type speed sensor, so each output pulse is a single cycle roughly sinusoidal pulse that varies in amplitude with engine speed - more speed=high amplitude (voltage). Signal is .5 to 5v.
The “A” pin is sensor ground, BLK wire, D7 on the OEM TCM conn.
The “B” pin is signal, WHT or BLU wire, D6 on the OEM TCM conn.
Both wires run straight to the OEM TCM.
This signal is only used for the transmission.
Your TCM should use this signal no problem.
 
BTW, here is the instructions on the TCU. page 5 talks about the RPM signal for it.
 

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  • tci-302820 instructions.pdf
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The ess of the rear of camshaft on 6.2/6.5 is always the two wire no matter wether it is the vacuum pump one or the low pro model.

There is always another option.
Gotta sometimes do a timing chain replacement but you can use ds4 timing chain with the 4 point wheel on it. Then the timing cover that holds the crankshaft position sensor- the ds4 equipped trucks have a 3 wire sensor but turbo equipped hmmwv (not hummers) use a 2 wire sensor for that location.

Try the ess on rear of engine- I agree with Glagator, I believe it will work. If it doesn’t you need to cps for a ds4 equipped truck.

Here is this about the difference:
 
You probably should splice the BLK "A" wire from the ESS to a wire on Pin 23 BLK/PNK
of the TCI module.
Then the “B” wire to Pin 12 YEL.
Many military 6.2/6.5 4L80 owners have done this and it works.
I have always wondered why the company never addressed using the ESS or a compatible CPS (2 wire military part).
At least I have not come across that info from the company.
 
The 2 wire military part didn’t exist when they made the controller originally.
I needed it because my 95 hummer was non turbo db2 ip. Hummer mounts turbo as the center mount system from a van. In 96 they went to turbo and also ds4- basically jumped to the van set up. When I put the turbo there I had to use a rpm sensor for my tcm and I snagged a few 2 wire cps from a junkyard and ended up modifying one from a Mitsubishi or something. Then later the military hmmwv started getting turbos- so they had same problem. Unlike me and junkyard diy-they just had the sensor engineered. Somewhere on this forum one of the guys found it- posted it- and even sent me one he removed. I have it on my parts shelf and when my engine goes back together I will finally install it instead of my diy one. Can’t think of anything right now- drawing a blank to who that was- hate this medicine but it helps my back. Probably just makes me forget I am hurt! Haha.
 
Ok. Cut the cut the connector off from the harness and spliced in pin A to pin 23 on the TCI (analog ground). And spliced pin B to pin 12 yellow rpm input but no dice. How can I test this ess sensor to verify if it’s good?
 
Twisted Steel Performance said:
You may have said somewhere but why are you using a different controller if the 93 controller is still in the truck?
Click to expand...
The trans is for a 96 and supposedly won’t work

Twisted Steel Performance said:
If you aren't going to use the stock controller sell me the prom...
Click to expand...
I might just do that once I can get this one to work

The OEM controller wa for the 93 trans that did some sort of cleaning cycle on the TCC if I remember correctly
 
The ESS should put out a 0-5v. pulsing A/C signal when the engine is running.
It is possible that that TCM must have a digital RPM signal.
I have no hands on experience with the unit and cannot find any info that will
verify that.
It is possible that the 3-wire CPS used on the DS4 IP engines would work.
Does your engine have the CPS hole in the timing cover and the reluctor?
 
Glagulator said:
The ESS should put out a 0-5v. pulsing A/C signal when the engine is running.
It is possible that that TCM must have a digital RPM signal.
I have no hands on experience with the unit and cannot find any info that will
verify that.
It is possible that the 3-wire CPS used on the DS4 IP engines would work.
Does your engine have the CPS hole in the timing cover and the reluctor?
Click to expand...
Unfortunately no, it has the older timing cover for the 93. no hole for the CPS.

I did tried ohm-ing the ess but only got a reading up in the mega-ohms. using my meter, grounding one side of the ESS and probing from pin b to pos on the battery it's passing through at 12v but doing the same with a test light did nothing running or not. also noticed it's passing a small amount of ground though the housing or block to pin b. with out pin a grounded if I probe pin b and battery + with my volt meter I see 8v. I know that's not a good way for a test though.
 
Having no RPM signal would make sense why the TCC won't engage. not sure if this is the cause of the hard shift from 1st to 2nd. It does shift into 3rd and 4th just fine, but no down shifting
 
I have a new in box crank gear and chain that came off my P400. Chris installed timing gears so no use for it. Also have a timing cover with the hole for sensor in it. If you'd like either for getting this to run I can give you a good deal.
 
@Glagulator I stand corrected. I "thought" it had the old timing cover installed but I got a closer look. when I first looked I saw the timing indicator tab that is for the DB2 for using a timing light and only assumed this was the older cover.

I crawled under the truck and found this... after scraping it off with a flat blade and a rag there is some sort of cover plate here. I also recalled seeing a sensor in the slew of spare parts I was give with this truck, I pulled out this sensor with a pig tail. Photos below. the last photo is a pic of the timing cover on the 6.2 block I have to compare to this one.

IMG_4820.jpg
IMG_4821.jpg
IMG_4823.jpg
IMG_4824.jpg
IMG_4822.jpg
 
DieselAmateur said:
I have a new in box crank gear and chain that came off my P400. Chris installed timing gears so no use for it. Also have a timing cover with the hole for sensor in it. If you'd like either for getting this to run I can give you a good deal.
Click to expand...
Thank you :) but I think I just found what I needed and had it all along. not sure if I have the right sensor, the one I have seems to be rather long.
if it's the right one, I need to find out how to wire it up to work. I might need a timing chain for it though. time will tell once I get all the grimlins worked out here lol
 
I will do that in the morning. we have some heavy thunder storms that rolled in. from the looks of that cover, it seems that it's hand made, there might be a sensor in there broken off. I hope not but I won't know till I get the cover off.
 
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