P38A Electrical issue

tarphenry · Feb 9, 2021

Hi all, on Saturday I did some shopping and on my way back , the car was at tickover at the lights and smoke appeared under the bonnet. I managed to get the car home and thought it must be the fuse board. However, further investigation revealed it was the wiring to the alarm klaxton. The 2 larger pins had melted .I removed the pins and encapsulated the plug to prevent further shorting and now I appear not to have any Heavac supply, just a blank screen. I will go and check all the fuses when it stops snowing ,but has any one else had this problem? any advice appreciated. Electrickery is not my thing thanks.

pwood999 · Feb 9, 2021

A few years back, the sounder on mine kept blowing fuses. Battery had failed and was shorting out. Disconnected it & no more problems.

pete12345 · Feb 9, 2021

Check relay 7 I think mine kept blowing

Grrrrrr · Feb 9, 2021

tarphenry said:
Hi all, on Saturday I did some shopping and on my way back , the car was at tickover at the lights and smoke appeared under the bonnet. I managed to get the car home and thought it must be the fuse board. However, further investigation revealed it was the wiring to the alarm klaxton. The 2 larger pins had melted .I removed the pins and encapsulated the plug to prevent further shorting and now I appear not to have any Heavac supply, just a blank screen. I will go and check all the fuses when it stops snowing ,but has any one else had this problem? any advice appreciated. Electrickery is not my thing thanks.

Think someone had something similar last week but giveaway was no comms to EAS

tarphenry · Feb 11, 2021

Hi, today I have checked every fuse twice both engine bay and under seat. none blown .I have taken relay 6 and7 out and taken the tops off both are working fine It seems as though the supply to the hevac has gone somewhere but I have no idea where. there is no burning or smell, just the supply to the alarm klaxon. I am stuck, does anyone have any ideas please Thanks

pete12345 · Feb 11, 2021

My fuse box was burnt underneath fuse 7 but had to remove it to see what was going on

tarphenry · Feb 11, 2021

thanks i will remove board again

Richdove · Feb 12, 2021

tarphenry said:
thanks i will remove board again

Something similar happened to my P38 a week or so ago. The connector plug to the alarm sounder had fried and blew fuse 44. This also took out the air suspension where a max 35 mph warning showed. I isolated the sounder and the fault cleared. Now the strange thing is that the HVAC has always shown the book symbol until this happened. I wasn’t aware the systems were connected but the fried alarm sounder plug on mine cleared the book symbol and has turned your screen blank. I’ve no idea what that could mean but someone here will. Pic of fried plug attached. Change fuse 44 10A anyway....

tarphenry · Feb 13, 2021

Exactly the same as mine. all the car works inc air suspension but no HEVAC strange. I will doble check all fuses tomorrow and see if I can find a solution. Thanks for the information

tarphenry · Feb 16, 2021

Weather slightly warmer today, and I notice that Nanocom will not power up. I am thinking that The short circuit may have damaged the BECM, but I have no way of testing this. There are no blown fuses or burning at the fuseboard. Is there any simple test that you know of?

pete12345 · Feb 16, 2021

Have you tried powering the nanocom through your computer as when you update it

tarphenry · Feb 17, 2021

yes, it powers up fine. thanks

pwood999 · Feb 17, 2021

tarphenry said:
Weather slightly warmer today, and I notice that Nanocom will not power up. I am thinking that The short circuit may have damaged the BECM, but I have no way of testing this. There are no blown fuses or burning at the fuseboard. Is there any simple test that you know of?

Check the 12V supply & ground at the diagnostic connector. Otherwise power the Nanocom using USB lead, and try connecting to ECU's.

tarphenry · Feb 17, 2021

thanks will do

tarphenry · Feb 17, 2021

tarphenry · Feb 18, 2021

Connected Nanocom through computer as advised but cannot connect with either HEVAC or BECM. have sent pm to Marty Uk to see if he is available to look at my BECM. He has a shop IP38 something I think ah well keep looking I suppose Thanks for all the assistance

pwood999 · Feb 18, 2021

If BECM is "locked" i.e. as from the factory, you cannot communicate with engine on. HEVAC is often problematic, especially if BECM has been "unlocked". Try with ignition on & engine off. Then try with engine running. Sometimes it takes a few goes !!

tomcat59alan · Feb 18, 2021

pwood999 said:
Check the 12V supply & ground at the diagnostic connector. Otherwise power the Nanocom using USB lead, and try connecting to ECU's.

Pin 16 is the supply and pins4 and 5 are ground.

tarphenry · Feb 18, 2021

thanks

tomcat59alan · Feb 18, 2021

tarphenry said:
thanks

From memory pin 16 is a brown wire that runs from the obd to the drivers side ,i think it has a splice in it ,it passes through the bulkhead and exits under the expansion tank,you have to open up the loom to find it, it continues to the fuse box I think, I was lucky to find the break before the fuse box.

P38A Electrical issue

Well-Known Member

Well-Known Member

Well-Known Member

Technician, Bodgit & Scarper Ltd

Well-Known Member

Well-Known Member

Well-Known Member

Well-Known Member

Well-Known Member

Well-Known Member

Well-Known Member

Well-Known Member

Well-Known Member

Well-Known Member

Well-Known Member

Well-Known Member

Well-Known Member

Well-Known Member

Well-Known Member

Well-Known Member

Similar threads