Adding to above, I’m also thinking about how to measure the HEVAC output voltage in case the board has hardware fault. I have a spare with bad display so the main board from that might help.
I can give you details of the motor drive chips if it would help. Bad display? Not the ZEBRA strip which can be replaced?
 
Probably the zebra yes, but never got round tuit. Are the motors direct from the chip, or any output transistors ? Was gonna look myself, but if you already have the info ?

Maybe I should move this & the previous posts to a separate thread.
Direct from OP Amp driver chips. I'll dig the info out this evening.
 
Direct from OP Amp driver chips. I'll dig the info out this evening.
It's raining again so here is the info on the chip that drives the blend and distribution motors.
L272 HEVAC chip.jpg
L272M pinouts.jpg

You can find the full spec on line.
 
Hoping to have the old gal back today from having FIP gaskets done but there is a problem. They couldn't stop it from leaking along the body. On and off 3 times and still leaks. Looks like hair line fracture in the FIP body. It was noticed some one had worked on it before as the tamper bolt in the top had been swapped. Good news Shaun has a good pump on another P38 and Monday he will swap it over for the one on mine to get me back on the road again. Glad I trusted him to do the job as he knows them inside out I isn't out to rip me off.
 
Hoping to have the old gal back today from having FIP gaskets done but there is a problem. They couldn't stop it from leaking along the body. On and off 3 times and still leaks. Looks like hair line fracture in the FIP body. It was noticed some one had worked on it before as the tamper bolt in the top had been swapped. Good news Shaun has a good pump on another P38 and Monday he will swap it over for the one on mine to get me back on the road again. Glad I trusted him to do the job as he knows them inside out I isn't out to rip me off.

From memory there's an oval section each side that cones off with a spring and an o-ring underneath. Could that be leaking and that is what you are picking up? The one on the engine side is awkward as ****.
 
Never seen that before. Someone must have really mullered that security bolt.
The guy who owned the P38 I had the engine out of was a welder and bit of a bodger. I wonder if he'd tried some kind of repair in the past and now its finally let go?.
I'm fortunate I am getting a known good replacement and all done at mates rates.
 
Today was prep work for the exhaust, turned out I missed some bits and pieces. And since I had not much motivation to get dirty, I emptied the car to get the new carpets in. This also means new wirimg for the second battery (some out lets in the trunk for camping, and some somewhere for a fridge and phones). And the box middle concolse went out, the radiondied a while ago, so I assembled the original one again, with a new cover from the upholsterer. Who will get some more work, the center carpet is missing the wholes for the parking break, transfercase and diff lock button for some reason... Well, I don't meed the full set anyways, so some carpets for the back will have to be sacrificed for that. And the door panels, a) because the speakers will go as well and b) because I picked the wrong color, still original but more brown instead of the beige mine had. Still looks good so, and fits very nicely with the new front seats! Pics to follow once everything is back in! Exhaust will have to wait for next week.

And the fuel issue is the fuel line, when I deplug it from the tank, it spils out just fine. I have some of the same hose left, that'll have to do until I can justify some better quality one.
 
The new (to me) 4.4 has been complaining; "EGR Flow Insufficient". So I decided to look into that and while I was there to remove the donut intake and inspect the rubbers to see if they were the cause of my sporadic low boost pressure issue. There was definitely a little evidence of EGR fouling to put it mildly.

IMG-2088.jpg

This is what happens with low mileage, short journey cars but please don't get me started on the merits of EGR!

IMG-2093.jpg

All nice and clean now. I scraped about 10mm of gunk off the MAP sensor while I was in there cleaning it too. I now have very reliable boost correlation errors so that is now working nicely again albeit highlighting other issues. Another step closer even if it feels like it's going slightly backwards sometimes.
 
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The new (to me) 4.4 has been complaining; "EGR Flow Insufficient". So I decided to look into that and while I was there to remove the donut intake and inspect the rubbers to see if they were the cause of my sporadic low boost pressure issue. There was definitely a little evidence of EGR fouling to put it mildly.

IMG-2088.jpg

This is what happens with low mileage, short journey cars but please don't get me started on the merits of EGR!

IMG-2093.jpg

All nice and clean now. I scraped about 10mm of gunk off the MAP sensor while I was in there cleaning it too. I now have very reliable boost correlation errors so that is now working nicely again albeit highlighting other issues. Another step closer even if it feels like it's going slightly backwards sometimes.
The low flow error will most likely have been due to the MAP sensor not reacting quickly enough, due to the coating of oily soot, there would still have been sufficient flow through the EGR despite appearances.
 

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