Ok so I have only owned this 2003 discovery 3 days now. And Cary around my little scan tool to clear the codes to clear the blinking lights and p0748 code. And for the most part drives normal far as I can tell. Occasional when I would pop in reverse would have to give it a little gas then I would feel it engage. So I decided to check tranny oil and it's level. Drained a tad and it was dark red didn't smell really. So popped the filler plug to see if low. And we'll atf poured out had it pretty level but figured I'll lower the rear and popped the plug and still oil came out. Soo put it back and drove it. Then that hesitation when popping in gear was there almost all the time and even at a stop light. Never got the p0748 during those few starts but got a p0741, which I have never gotten till drained some oil...Soooo decided to do filter change. And found no rubber o ring on the large port where it seats in the valve body. Put new filter in and filled with new oil and Lucas conditioner. While I still get the p0748 no more hesitation and having to give it gas to engage. With the proper oil level.
P0748 (M) (S) flash update sorta
- Thread starter Mp1976
- Start date
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Disco Mike
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We should talk, looks like you do not know how to check the ATF level or refill.
Hey mike. With vehicle level I filled till oil started pouring out of the full hole. I plugged it and started the vehicle with break applied ran through all gears on shift knob. Shut vehicle off and then opened fill plug to again add more oil till it once again poured from the fill hole. The thing I was pointing out was that the tranny filter whom ever changed it last had no oring on the back side between filter and valve body. Which was clearly sucking air causing that p0741 code and the delay before engaging in drive or reverse. That person overfilled the tranny to the point where oil covered the filter and missing oring. I replaced the filter with the oring and with the oil at proper level issue is now resolved with that delay and p041 code. Mind U that code only appeared once I drained some oil and it went below where the oring was missing allowing again for it to suck air. I am pretty sure I have filled it properly lemme know if I did.
Thanx
Thanx
Last thing I read says with vehicle still running after going through the gears with break pressed to fill it... Is that what u recomend mike ? Also how do I know what transmission I have that manual lists ZF4HP22 - 24 how would I know if I have the 22 or the 24. ?
Disco Mike
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Always check the level or fill the tranny the second time with the engine running or you will lose fluid from the tranny.
Mike so I'm looking to replace the pressure regulating solenoid in the tranny. I know which one it is and where it's located. And have found parts online. Some you will find as kits selling all 3 shut soenoids like this http://pages.ebay.com/link/?nav=item.view&alt=web&id=200887129614 or single solenoid. Now what I'm trying to find out if all 4 solenoid a are the same the pressure regulating solenoid does seperate from that small body that link shows. And other pics I have seen look like they are physically the same. But I am not sure. I Just wanted to buy the one solenoid for $80 that's why I'm trying to find out. Any ideas?
Now what?
OK soooo i dropped the valve body there is link to pics so the pressure solenoid is different than the rest.. simple ohms test to each one suggests they area all ok.. with the Pressure solenoid having the least resistance.. so i have a 12v supply for my soldering projects so i adjusted it to 5 volts hit the pressure solenoid quick taps and hear it clicking.. upped to 9 volt and clicks louder and you see the valve open blowing my mouth through the hole it open and closes. didn't do that long didn't want to damage it just incase.. so Im stumped.. i unplugged there TCU and checked continuity on each pin that goes down to the tranny plug all good to all pins... ANY iDEAS?? Battery voltage on this 2 month old battery from the load test autozone did was 12.7 and said it was good. I get this code and blinking M S just about overtime i start it.. after driving for a while sometimes i get lucky. comes on right at start up.. I clear it and it drives fine...
https://www.dropbox.com/sh/b1bmsajw8j4zupf/AADSs2DdUS_FF_v4G2tiUju-a?dl=0
OK soooo i dropped the valve body there is link to pics so the pressure solenoid is different than the rest.. simple ohms test to each one suggests they area all ok.. with the Pressure solenoid having the least resistance.. so i have a 12v supply for my soldering projects so i adjusted it to 5 volts hit the pressure solenoid quick taps and hear it clicking.. upped to 9 volt and clicks louder and you see the valve open blowing my mouth through the hole it open and closes. didn't do that long didn't want to damage it just incase.. so Im stumped.. i unplugged there TCU and checked continuity on each pin that goes down to the tranny plug all good to all pins... ANY iDEAS?? Battery voltage on this 2 month old battery from the load test autozone did was 12.7 and said it was good. I get this code and blinking M S just about overtime i start it.. after driving for a while sometimes i get lucky. comes on right at start up.. I clear it and it drives fine...
https://www.dropbox.com/sh/b1bmsajw8j4zupf/AADSs2DdUS_FF_v4G2tiUju-a?dl=0
also checked no short to ground on any if the wires running from TCU to the Tranny and none grounding on the valve body.... could this just be a bumm Alternator ? as long as my multimeter was correct when i checked the batteries were low and i got a 14.05 while vehicle running.. should be around 14.3 is what i am reading.. maybe i too this all apart for nothing ...lol well maybe ill re assemble and check my alternator again..
