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Codes. Truck won’t move

C

CBR consulting

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2005 gmc c5500.
allison 1000
Story about this truck. I purchased it with the assumption it needed a trans. Since then I have realized with the help of DHD. (Dirty hooker diesel) that someone had made a mess of the valve body.




Valve body was gone through with DHD in Michigan. New solenoids, new internal harness, new pressure switch.

new NSBU
New ignition switch

I have installed the the valve body.
I have no reverse or drive still. If you unplug the trans side of the harness, reverse and drive come back.

I have ohms each wire going from the TCM red connector to the trans side of the 20 way plug. Each wire reads 0.08. Which I’m assume is correct for the harness.

I pulled the complete harness back and didn’t see any bad wires other than an open wire on the turbine sensor. Which I have repaired.

I borrowed a TCM from a running truck and no changes.

I’m currently getting codes po713 and p0748.

Does anybody have some help on this
 
P0748 is for the pressure control solenoid. It should ohm out to 5.5 ohm at pins 22 and 23 of the red TCM connector.

P0713 is for the fluid temp sensor. It should be 3400ohms @ 68*f measured across pins 10 and 20 at the red TCM connector.

As far as testing wires I like to use a head lamp bulb and load the circuit and make sure it can carry amperage. Ohms testing can get you in trouble when looking for a bad wire. It does work well for testing sensors or solenoids thought. I would Ohm out the TFT and PCS and see if they are in spec, If not then I would retest your wiring.
 
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After you do the testing mentioned above, also look at all of your grounds. P0713 is Trans fluid temp sensor A circuit high indication of an open circuit. you should be getting a +5v signal going to the sensor as well as the others too and then the return signal would be what the sensor is telling the PCM. Grounds can play havoc on electrical systems

I found this online that might help.
www.obd-codes.com

P0713 Transmission Fluid Temperature Sensor A Circuit High Input

How to diagnose, repair, and info on causes of a P0713 transmission trouble code which means a high input in the trans fluid temperature sensor circuit.
www.obd-codes.com
 
dbrannon79 said:
After you do the testing mentioned above, also look at all of your grounds. P0713 is Trans fluid temp sensor A circuit high indication of an open circuit. you should be getting a +5v signal going to the sensor as well as the others too and then the return signal would be what the sensor is telling the PCM. Grounds can play havoc on electrical systems

I found this online that might help.
www.obd-codes.com

P0713 Transmission Fluid Temperature Sensor A Circuit High Input

How to diagnose, repair, and info on causes of a P0713 transmission trouble code which means a high input in the trans fluid temperature sensor circuit.
www.obd-codes.com
Click to expand...
Thats a very good article and procedure.
My only suggestion would be to remove the sensor, place it in the wifeys favorite cooking kettle along with the water, have the jumpers hooked to the multimeter on ohms scale, then begin heating the water, also with the wifeys cooking thermometer within the kettle of water, to monitor the water temp and observe that the meter is responding accordingly.
There most likely, out there on the net, might be the temp to multimeter reading correlation chart.
 
Change of plans


I forgot I had the harness going into the trans unplugged


Still no gears


So with that said. I plugged it back in.

With the scanner and ignition in key on position . I’m able to clear codes. Once codes are cleared. P0748 comes back instantly.

I just have an Auto link scanner. Do we think I need something better to get this out of limp mode or is it definitely wiring.

NSBU switch is new But it didn’t have the metal retainer on it ?

Ignition switch is new aswell


When put into reverse. R line. indicator flashes

D. No indicator appears.

3,2,1. Line under flashes
 
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CBR consulting said:
Change of plans


I forgot I had the harness going into the trans unplugged


Still no gears


So with that said. I plugged it back in.

With the scanner and ignition in key on position . I’m able to clear codes. Once codes are cleared. P0748 comes back instantly.

I just have an Auto link scanner. Do we think I need something better to get this out of limp mode or is it definitely wiring.

NSBU switch is new But it didn’t have the metal retainer on it ?

Ignition switch is new aswell


When put into reverse. R line. indicator flashes

D. No indicator appears.

3,2,1. Line under flashes
Click to expand...
Wish I could edit the replys


Testing for code p0748

Tested both lines for shift solenoid A.

Both light up the light bright and the same

Pin 22/23. Ohm at 6.8 on the whole system

Pin L/m of the internal harness only, ohm at 6.8
 
what all was done to the trans again? and when did this problem occur? I was reading on this code and found this online. I am wondering if there is some obstruction keeping the solenoid from functioning.

P0748: Code Meaning, Causes, Symptoms, & Tech Notes

<p>The P0748 code indicates a problem with the Pressure Control Solenoid 'A' electrical circuit in the transmission. This solenoid is responsible for
www.engine-codes.com www.engine-codes.com

1695500919705.png
 
So I bought this truck from local nursery. They had limped the truck home from a job and just decided to sell it.


I pulled The valve body and was gone through at DHD. Dirty hooker diesel in harbour beach Michigan


The valve body out of that truck was toast Tyler said. There were scores on the solenoid walls. And someone had the valve body apart

So he put together a replacement valve body he had. With new solenoids, new harness , new pressure switch



I have also done

New internal filter, new spin on filter, new ignition switch and new NSBU switch, NSBU switch didn’t come with the metal retainer on it though ?
 
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Issue wasn’t fixed

Still stuck dead in my drive way


What makes me think what’s is going on cause when you discount the plug going into the trans you get some gears.

Once you plug it back in you dead again.


I’m pretty mechanical incline but if there’s one thing I hate it’s electrical.
 
when you disconnect the harness from the trans, it forces the trans to go full 100% pressure in the lines. what I think is happening is the ECM can't read the line pressure from the trans sensors properly or there is a problem on this solenoid. weather the actual solenoid or something in the valve body. I'm no expert on trans by any means but if you can get the pin out on the trans plug and ohm out the solenoid in question and compare it to a new one maybe that will say something if the actual solenoid is the issue.

I'm also not sure if the solenoid is accessable with only the pan off or if the valve body has to come out but if you are able to drain the trans saving fluid to reuse, then pull the pan to check the harness inside along with pulling the solenoid and sensors looking for any debris scorring and whatnot might be worth while. if you go in there, look for anything in the pan too. anywhere you see what looks like black or grey residue within the red fluid, that is debris that can collect and cause issues. it's usually clutch material. since the valve body has been into, and I'm not saying DHD did anything incorrectly, but these bodies are so particular that if a piece of dirt or sliver if material the size of a single hair got in there it can cause issues. accidents happen in any shop regardless of the knowledge or reputation of the shop.
 
dbrannon79 said:
when you disconnect the harness from the trans, it forces the trans to go full 100% pressure in the lines. what I think is happening is the ECM can't read the line pressure from the trans sensors properly or there is a problem on this solenoid. weather the actual solenoid or something in the valve body. I'm no expert on trans by any means but if you can get the pin out on the trans plug and ohm out the solenoid in question and compare it to a new one maybe that will say something if the actual solenoid is the issue.

I'm also not sure if the solenoid is accessable with only the pan off or if the valve body has to come out but if you are able to drain the trans saving fluid to reuse, then pull the pan to check the harness inside along with pulling the solenoid and sensors looking for any debris scorring and whatnot might be worth while. if you go in there, look for anything in the pan too. anywhere you see what looks like black or grey residue within the red fluid, that is debris that can collect and cause issues. it's usually clutch material. since the valve body has been into, and I'm not saying DHD did anything incorrectly, but these bodies are so particular that if a piece of dirt or sliver if material the size of a single hair got in there it can cause issues. accidents happen in any shop regardless of the knowledge or reputation of the shop.
Click to expand...
I did a reading on the solenoid of question And it reads 6.8 ohms
That’s going through the internal harness
 
I don't know what the reading is for a new or known good solenoid is. if we can find that info we can rule out this and a bad solenoid.
 
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