THis is my first post. I do have a video to post and will get it up ASAP. Here is the story:
Been working on my Disco for sometime. Been putting less than 5K a year on it over the bast 4 years. New rotor, calipers, break lines, shocks, muffler, exhaust manifold, transmission oil line, trans oil cooler.... it goes on. First real car I have worked on extensively. I have the shop manual. So, I finally think it is all together. Inspections all good, all the little things taken care of.
I drive about 20 miles with a stop for dinner. within 1/4 mile from home the engine stops while traveling ~25mph. Cost the car to a parking stop. No fuel pressure, no spark and some strange clicking noises coming from 3 points. I have no experience with electronic diagnosis.
Replaced crankshaft sensor. could have explained fuel and spark but not other issues. Didn't work. Toed the car home. 3 days later I proceeded to make a video, turned the key and the engine started. Assumed maybe the sensor kicked in??? Wishful thinking. within 5 miles engine died again. This time the check engine light came on first.
So now the car sits. I attempted to pull codes but get an error. That makes me think ECU?? But before i throw parts and money at the problem, asking for help makes more sense. Please watch the video.
The relay that is clicking was disconnected when the engine fired up after the first failure.

This should be the video. was not able to add it as attachment in forum. File too large??
I should note that i do have access to two similar Discos at the junk yard.
Thanks so much for any direction provided on this one. I will check daily for posts.
Cheers!

 

Remove the ECU from it's location and remove the covers. Check for corrosion (water ingress) first before you do anything else. That is, if this is even ECU related. Being that your in the rust belt the covers can rot. If you have a cover issue use silicone to seal them to the ECU frame. If you swap the ECU out snag the green plastic box from under the donors dash on the passenger side. Some units need the AS10 alarm married to the ECU to function as the VIN is hard coded to it.

Good luck, post what you find.

 

If you can't pull codes then either the wiring, ECU or scanner is damaged. Check your grounds first. Check the ECU for corrosion. Check your scanner on another vehicle. I also wonder if it may be immobilization related. Sometimes the immobilizer can malfunction causing no start situations. I wrote a sticky on bypassing it.

 

Thanks ihscouts....you state "if this is even ECU related." What are other options?
Thanks as well Tyrrell. The scanner works. Not that. The Disco did live in lower Michigan for years and has a good deal of rust from all the salts on the roads. So I will work on the ground points first.
THinking about the rust, moisture, and grounds...I wondered now that the summer humidity has broken could that have had something to do with this and guess what, the engine started right up this morning. After 2 weeks of sitting, it starts. The check engine light is on, will pull codes later (left scanner in my lady's VW ignition coil misfire due to moisture). So, twice the engine shuts down while traveling (25 & 50mph) and twice it starts up after sitting for a couple of weeks.
Tried removing negative terminal frame ground for cleaning...rusted fast. Good place to start.

 

Eric posted the other issues you might be having. One other issue that you will have an opportunity to look at is the large Molex connector on ECU. Aluminum pins, look for corrosion there, it will look like white dust. Dielectric grease them before you button it up. Don't slather it on but dab it on each pin otherwise you'll be making cross connections through the grease.

On the ground connections once you have cleaned them and reinstalled use a regular grease to cover them, gob it on. I don't think the engine quitting is so much speed related as it is road related, bumps. When checking the grounds inspect the copper wire to crimp on connector. Bad corrosion, cut connector off, cut back to clean copper and use new connectors. Don't use the cheap electrical all in one tools to do the work, use a Klein crimp tool which all electrical supply houses have. I went as far as to solder them to keep as much moisture out and off the copper then gobbed on the regular grease.

So much of the truck is grounded that weak connections cause overheating in every device on that ground leg. Huge pain in the butt to replace melted relays, rear light housings, wire loom and not to mention the fire hazard. I had one relay go up in flames due to a windshield leak and laid a nice coat of black soot on every horizontal surface not to mention a new smell to freshen up the interior.

 

Like they said, corroded groungs are a big problem. I had to totally redo the one on my starter. Forget cleaning off old grounds, make new ones!


Also go the tab at the top of the page called TSB & RECALLS and scan thru those. Pins tend to unseat on various connectors. Lots of info there you will want to check out on your truck.


If you can snag spare ecu's and the matching alarm ecu reasonably do it, MAF's too!


Also the circuit boards are prone to bad or cracked solder joints.

Water ingress is another issue.

 

My bet is on corrosion. I had a similar issue a couple of years ago. Turned out the was a rust hole the size of a quarter in the ECU.

 

Thanks for the input. Update, finally had time to pull the ECU. Rust has eaten through the wheel well. The entire bottom of the ECU has obvious degrees of corrosion. No excessively large holes though a few pinholes across the bottom. I assume the metal would be considered porous at this state.
I could not remove the top or the bottom due to screw(s) binding and the heads crumbling with the lightest torque. One side had all but one screw removed so i could get a peak. a good deal of corrosion residue coming out.
So, how to repair. sealing the edges with silicon. paint the box with some type of rubberized paint or tar. not sure what would be best. Best woiuld be to rebuild in new box. early searches show nothing available. Off to work on the ground points.
Thanks again for the help.

 

Contact paulgrant@mac.com. Tell him what year you have and ask if he has an ECU and AS10 pair to sell you.

Much easier than trying to find out what components are good or bad on the board.

Use bed liner from Wallymart or Meijers to coat the new box after you give a very light seal of silicone on both covers. Don't cover the factory pin-hole since it allows temp/pressure difference to equalize and not cause internal condensation.

Good luck.

 

Did replacing the ECU fix the problem? My Disco is making the same noise and I'm about to go check it's condition right now. Corrosion out here in NYC is killing my truck