Have a high amp drain it kills the battery within about 3 days. when I pull the transmission fuse in the PCM the drain goes away. I don't know how to read the schematic or I could trace the wires down myself, but problem is from the tranny fuse to where ever those wires go I think.

what ive checked.
fuse is good
relay is good,
PCM on bottom looks good no corrosion,
tranny and all sensors are new and test good.

 

You're gonna hate the fact that the only things downstream of that fuse are that fking relay that I've been after you about, and then beyond that the transmission solenoid assembly.

So: We want to return your rig to its as-built condition for this test, so rip out that mufkin jumper and any/all other hacks, workarounds, and/or aftermarket components that might be installed, and put everything except that transmission control relay where the factory originally put it, fuses and all. With everything except the transmission control relay right where the factory put it, and nothing in there that the factory didn't install, measure the drain. Nothing else. Just that.

Report the result. Don't analyze, don't get out in front. Just report the result. I will walk you through the troubleshooting process logically and methodically, and we will solve this problem, but ONLY if we can get a connection from my brain to your fingers and eyes that we can both rely upon. That and a known good multimeter, anyway.

 

Here we go again.

I think there is the main problem. As i said, UnregisteredUser and others STOP using jumpers!!!!!!! The fuse is before the relay, It is for a over amperage issue in the circuit. The circuit goes like this, fuse relay, transmission solenoids then pcm. That is the loop. I'm working from memory so forgive me if it's not to the letter but it may give you a better understanding. The relay has a primary side and a secondary side, The primary side has 12v+ going to it and the pcm controls the (-) to turn it on. The secondary side also has 12v+ and it goes to the trans solenoids when the relay is engaged. What you may want to try is disconnect the harness on the side of the trans over night to see if you still have the drain. There should not be any power going to it when the truck is off(relay disengaged). Might be a good idea to get a new relay, That would rule out having an issue with it. I know you said you have to pull out the fuse to stop drain. If drain is still there disconnect all leads going to the pcm. If drain stops the pcm is keeping the relay engaged even when the truck is off. If you still have drain with both trans and pcm disconnected your issue is elsewhere. Keep in mind a bad diode in the alternator can cause battery drain when the truck is off. But the trans fuse has nothing to do with that so i doubt that's the problem.

 

ok i have truck back to factory. when I did the amp draw test I had 1.58 amp draw.i THINK I found the amp problem, I hit the hood light and it flickered,, those mercury activated switches have had problems for years.! so I disconnected it and the amps dropped to 0.58 amps. then I started pulling fuses. when I pulled the IOD fuse it dropped to 0.08 then I pulled the power lock fuse and it dropped to 0.02 amps. then pulled all other fuses with no effect. sooo I THINK the hood light may have been my drain. seems to simple but we will see.
NOW the P0753 (tranny electrical) code is back.

 

Under hood lights are notorious for that kind of behavior. Usually, all it takes is repositioning the switch.

 

been a pain for years. so now to the orginal problem, the P0753 issue. I hope the amp drain is solved

 

ok i have truck back to factory. when I did the amp draw test I had 1.58 amp draw.i THINK I found the amp problem, I hit the hood light and it flickered,, those mercury activated switches have had problems for years.! so I disconnected it and the amps dropped to 0.58 amps. then I started pulling fuses. when I pulled the IOD fuse it dropped to 0.08 then I pulled the power lock fuse and it dropped to 0.02 amps. then pulled all other fuses with no effect. sooo I THINK the hood light may have been my drain. seems to simple but we will see. What is "normal" drain?


NOW the P0753 (tranny electrical) code is back.

Time to move on to the p0753 problem.

 

Good news on the drain problem. I was expecting something easy there and I'm glad it was.

Now for the trans electronics code: Take up your multimeter, set to DC volts, and probe negative to pin 85, positive to pin 86 of the transmission control relay. Turn the ignition key to run, record the measured voltage, start the engine, record the measured voltage, shift into any drive gear, record the voltage. Shut 'er down, remove the meter.

We're road tripping this weekend, so here's the next step:

IF you recorded battery voltage with the truck in gear, insert the transmission relay, clear the DTC's, drive it a while to see what happens.

If you didn't record battery voltage at that point we need to continue troubleshooting as follows: Again with the multimeter set to DCV, again in each of the three configurations (key to Run, then engine running, then running and in gear) negative probe to battery negative, positive probe to pin 86, record voltage. Then, positive probe to battery positive, negative probe to pin 85, record the voltage.

Either way, report back. We're making progress now!

 

P0753 Trans 3-4 Shift Solenoid/Trans Relay Circuits

Tie the copper lead of a wire around the terminal of the relay then put it back in. That's a good way to tap into it with out flipping over the panel with the relay installed. Just make sure it don't touch anything else.

 

ok I had voltage
dc volts from pin 85/86 key on 0.10 volts
eng running 85/86 13.04 volts
in any gear no change still 13.04
as soon as I deleted the code 2 came back 0753 and 1765 I deleted them again only the 0753 came back, then the 3rd time I deleted them, 0753 and 1765 came back. the fourth time only the 1765 came back. 5th reset 1765 only came back.all this done in park eng at idle. I decided to put it in drive and test after deleting all codes I ended up with 0753 again. did this 3 times to make sure and 0753 came back.


Hope u have a good road trip