Hello everyone I am starting a new thread on this subject because I believe I have found this issue to be only at cold starts
My MS lights flash and I go into limp mode when my truck is started from a cold start usually when the temperatures are below 15°C. (59 Fahrenheit). Which is not even that cold. I get Error code P0748 “pressure control solenoid a electrical”. If I let the truck run for one minute, shut it off and restart the lights no longer flash and I’m no longer in limp mode and all is fine. And I am fine for the rest of the day is this only occurs on morning starts I have tested my battery at my local parts shop and it past 800 cold cranking amp’s test.
However It is An economy brand battery which is only one year old and it came with the truck.
But from my knowledge the battery would be the only thing triggering the ms lights during the cold start.
Can anyone think of anything? The battery did fail the low test at 900 cold cranking amp’s. Could this be the issue? Thanks

 

Just bumping this to see if anyone can help

 

@Oshawa_D2 put a mutli meter on it 1st thing before starting, I bet the voltage is way low. Mine will crank at 11.5 volts,and start but I will get M&S lights every time. Let it run for a minute or 2 and it is fine turn off an restart and it is fine. My Disco sits a lot and I have a slow drain I just keep a smart battery charger on it.

 

Check your cables, make sure there clean and tight if they have a poor connection you will get it also.

 

What you just explained describes my condition exactly I can run the truck for one minute turn it off Then start back on and everything is OK. However I run mine every day so it’s not like its sitting around. I will check the voltage prior to starting next.

 

The cables on the battery are nice and tight. There is also a ground cable that runs to the side of the alternator and that’s nice and tight also

 

@Oshawa_D2 when you check the voltage

Check it cold engine off that will give you the battery charge this should be in the mid to high 12's
Then check it running that will tell you the alternator output at the battery this should be 13.4 or higher if it is low check with the multimeter positive to the alternator and ground to the block that will give the output at the alternator

 

cold engine in the morning I checked it was 12.4 and with the motor running It was 13.6
if I run the truck for literally 30 seconds turn it off and started back up the lights disappear. The error code that I get while the lights are flashing is P0748. I looked it up and that error code states

* Pressure regulating solenoid (MV 4), open or short circuit

Not sure what that exactly means and how it is affected by a cold start and then remedied 30 seconds after the start.

 

Page 44-19 of the Rave indicates a that P0748 is a transmission solenoid fault, but you should have hash shifts if it is.

I would start by checking all grounds the ecu's in these are very fussy about grounds, make sure to check the one on the firewall on the drivers side.
As well check for any vacuum leaks.

But that code sounds familiar.

 

@The Deputy you posted here about a possible solution https://landroverforums.com/forum/di...e-p0748-81677/ where is that connector ?