MEP-805B - no power to the ADC100 Electric Actuator

Gents, I'm not getting power to the ADC100 electric actuator on my MEP-805b, so of course it won't start ... I've read through all of the similar threads that I can find, here and elsewhere on the IntraWebs. Just wondering if my genset problem is obvious to anyone out there. My MEP-805B cranks, but wont' start. I have good fuel pressure all the way to the fuel shut off actuator (ADC100) on top of the injector pump. I did run the test to the fuel shutoff solenoid lead and got correct readings (correct ohms and no continuity). I checked the female side of the fuel solenoid plug (the plug not connected to the ADC100) and got no reading -- nothing -- when cranking the motor. I jumped the fuel solenoid, got he familiar metallic "click", and the motor fired right up. So, what I know is that the generator is not sending the correct signal (no signal actually) to the fuel shut off solenoid. I've done the correct start up procedure, holding the fault switch for two seconds before I crank, so it's not an operator head space and timing issue. The CIM displays no errors, but while booting shows an "Port reads 78 ... Cable disconnected ... " message. I have not yet removed the backplane and done the recommended cleaning, but will do so. Again, just wondering if anyone has had the same issues, with the same "Port reads 78 ... Cable disconnected ... " message … just hoping I can save some time. Thanks much!

I did get advice from Guyfang (thank you!), and will go out to the generator right now to see what lights I get ...

Here's what I got from Guyfang that I'll check on now ...

Have you checked the Mag Pickup?

Guyfang said:

Have you checked the Mag Pickup?

Click to expand...

That should be the first step of any jenny trouble shooting..... coolant low? check the magnetic pickup... rod sticking thru block? check magnetic pickup

Nope, I haven't checked the magnetic pick up, but I'm going in to the TM now to find out what it is, where it is, and how to test it. Thank you!

GIJoeCzar said:

Nope, I haven't checked the magnetic pick up, but I'm going in to the TM now to find out what it is, where it is, and how to test it. Thank you!

Click to expand...

page 384 in the -14. set at 2-3v.

Gentlemen, Thanks, very much, for your help. So, I pulled the magnetic pickup and although it looks fine, I'll test it per the TM today; 1-1.5V is what the manual states, but I'll be happy to see anything come out of it within reason. I've attached a few pictures for reference.


There are three photos inside the control box, the first photo shows unit with power on, but generator control in off position, the second photo shows unit with power on, and generator control in "start/run" position, the third photo shows unit with power on, generator control in "start/"run" position, and having just held the fault reset button for two seconds. They don't match the documents guyfang sent to me, so clearly I have other problems.

Screw magnetic pickup (4, Figure 4-30) into flywheel housing until pickup bottoms out on flywheel. Back magnetic pickup out 1 1/2 turns. Tighten locknut (5).

Adjust magnetic pickup (4), 4.13.3.d.

Set multimeter for VAC, and connect multimeter positive lead to terminal B of P13 and negative lead to terminal A.

Set MASTER CONTROL switch to ON and crank engine with DEAD CRANK switch. Observe
multimeter. Indication should be between 1.0 and 1.5 VAC. *edit 2.0 and 3.0 VAC*

If indications are not as above, back magnetic pickup out 1/4 to 1/2 turn. Retest by cranking engine and observe multimeter voltage.

Just got a mail back from the man I call Obi Wan. He told me, he personally now tell the army folks, 2.2 to 2.5 volts AC. All the years I worked on them, I used 2.5-3 volts AC, and it seemed to be good. And I got this info from Obi Wan. I have been out of the biz, since 2010, and it seems things have changed. He is going to send me a list of what the readings should be, for several different gen sets. Will post it ASAP.

GIjoe,

as as you can see, the mag pickup has been set toooooooooooooo close to the flywheel, at some time. Make sure that when you check it, it meets the spec's. Then take your time readjusting it. Better to readjust it several times, then grind the end off.

if it ends up that mpu is bad... its not an endall, those are an easier part to find. A big truck parts house will have them, they are used as speed sensors on the tranny. Just get the right diameter and thread pitch. There is nothing special about the mpu, it is a magnet that says, yes no yes no yes no yes no, and that makes voltage to send to a computer

Roger all; I did notice it had been set too close, and I did reset it according to specs (tighten securing nut at 1.5 turns out from bottom with flywheel), but I somehow missed the part about backing it out again by 1/4 to 1/2 turn and trying again. I'll give this a shot and see what I come up with (have to enlist my better half as I'm not an octopus)

Again, my board readings (red and green lights) don't match what they should be, so I'm guessing I'm not going to be so lucky as to simply replace the MPU and it fires, but, who knows ...

OK, I wasn't sure to test for AC volts or DC volts (I'm guessing DC volts) and I wasn't sure which pin was A or B, so ... I tested it all four ways -- DC volts multi-meter prongs one way then the other, and then AC volts multi-meter prongs one way then the other, and, wait for it, you both knew what was coming ... nothing, nothing, nothing, and ... nothing. I didn't make the time to back the MPU out a 1/4 or 1/2 turn, because I think that I should simply start with a fresh MPU and go from there. I have part number MSP675C for the MPU, and I say them on the big auction site for $20, but that would take a month as it would come from the Kong, so ... armed with the MPU and part number in hand I'll hit my truck parts place tomorrow and see if I can find one. Thanks again for your help!!! It would be SOOOOOO nice if the fix were this simple ...

VAC= volts AC

my guess is the mpu was on its way out and the good mech skrewed it in to get the volts needed, and was too close and rubbed just a bit

if the parts house looks at you funny, tell them an 03 kw eaton fuller 18918b,i am pretty sure thats the right size, Kw, not peterbilt, petes mpu is smaller

OK, I certainly will; thanks again for the assist!

mep 805b mpu diameter .75"

03 KW 18speed tranny mpu diameter .75"

Plugs looked exactly the same as well, the KW mpu appeared shorter, but it does have a very beefy bracket that it mounts in.

Well, I finally got around to messing with the MEP-805B again and I'm quite certain I know why someone ground the head of the magnetic pickup unit. I purchased a new one, installed it per the instructions, and dead-cranked the motor with my multi-meter set to AC volts and ... nothing, no reading whatsoever. SO, I put another known working multi-meter on the terminals of the mpu and cranked the motor again and ...... nothing. So, I adjusted the mpu out one half turn (I did this three separate times), cranked the motor and ......... nothing. I then re-installed the mpu, backed it out one full turn (instead of 1.5 turns), cranked the motor, and, you guessed it ........... no reading whatsoever. My two questions are (a) any idea what might be the problem and (b) how do I conjure up a 2.5 AC volt power source to jump the mpu leads so I can at least determine if in fact the mpu is the problem. Time is a factor here, so at some point -- fairly soon -- I'm going to cut bait, dismantle this thing, sell the known working parts (motor purrs like a kitten), and call it a day (really a few weeks).

Where were you making your mesurments from, when you were adjusting the MPU?

Here is a video, this is not of a 805, but the process of testing is exactly the same. As the video shows, my mpu needs to be adjusted.


https://youtu.be/fb0fmCUZj7Y

That is exactly what I did and how I did it (your video) ... no reading whatsoever. What are the chances of having a bad mpu, then buying another one that's bad -- not very likely. I can't for the life of me figure out why it wouldn't be putting off a reading, but again, it tells me why the mpu that was on the generator had the head rubbed, because the trooper who worked on it was having the same issue as me. Any idea on how to cheaply generate 2.5 VAC, so I can trick the generator into thinking that my mpu is working? That would tell me a lot.

Thanks very, Very, VERY much for your help!