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Staying Grounded

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Read this, this morning.  I found it interesting.

Believe in Bad Grounds
Tom's Story

I have read manufacturer tips about checking ground connections before replacing electronic parts. I have even written articles about checking ground connections, adding ground wires, and using voltage drop testing before replacing parts. But despite all my wisdom, I still went ahead and unnecessarily replaced the Engine Control Module (ECM is Ford's EEC-IV) on my wife's 1993 Ford Tempo when the ECM really "just" had a ground connection problem.

A Hemmings article on Ford's EEC-IV says it is known for "extreme sensitivity to ground circuit issues" and "a high-impedance ground would drive it crazy." Rather than feeling too guilty for not practicing the grounding rules that I preach, I feel like the "crazy" EEC-IV has taught me additional Yoda-level grounding knowledge that is valuable to owners of other computer-equipped vehicles.

Parts that temporarily fixed the problem
Parts that temporarily "fixed" the problem

1. With grounding problems, new parts may bring relief, but that relief may also be increasingly short lived. A grounding problem can persist for years. Replacing parts can temporarily fix/hide the problem for years as well. Disconnecting/reconnecting electrical connectors, removing/reinstalling mounting bolts and/or a fresh, completely in-spec. part might be enough to improve the ground connection. But, the root-cause grounding problem might still be there and possibly worsening.

The fuel pump in my wife's Ford would stop (no sound from fuel tank). A new Ignition Starter Switch fixed the problem for a few years and a new Fuel Pump fixed the problem for a few more years, cleaning the electrical connector on the Body Control Module (BCM contains the fuel pump relay) fixed the problem for another fourteen months, replacing the BCM fixed the problem for two days, replacing the ECM fixed the problem long enough for one round-trip to the grocery store. Forums are full of posts from Tempo, Mustang and other Ford EEC-IV owners with nearly identical stories. They gradually replace all the major parts connected to the circuit, reporting temporary success after every install. Sometimes, they start replacing the same parts for a second time and those new parts fix things for an even shorter period of time or don't help at all.

2. It looks exactly like a desktop computer problem, but that might mean your old PC just had a grounding problem too. After a cold-start, the engine in my wife's Ford would run for about ten minutes and then the fuel pump would shut down. After a minute or two, the fuel pump would come back to life and the engine would restart and run another three minutes. The Ford's OBD I diagnostic connector conveniently has a pin that turns on the fuel pump whenever it is grounded. The fuel pump always ran fine with that pin grounded, so it was not the fuel pump overheating. (The ECM turns on the fuel pump relay by providing a ground, so manually grounding that OBD I connector pin might provide a good ground connection to the fuel pump relay that the ECM no longer has on its own.)

I guessed that an electronic component on the computer's circuit board was overheating, shutting off and restarting after cooling down. That is when I finally replaced the ECM and enjoyed one trip to the grocery store before the fuel pump stalling started again.

Old PCs and laptops also sometimes repeatedly shutdown and restart as they heat up and cool off. The last time I had a PC do that, I called the computer manufacturer and was told to unplug all the cables and hold the computer's power button in for thirty seconds to "drain away static electricity." The PC was not dead, it was just experiencing something similar to a grounding problem.

3. Accept the solution even if you cannot adequately explain it. I spent six long years studying electrical engineering, and I wanted an elegant solution. I had replaced, tested and/or cleaned every part, connector and ground connection I could reach. In the '80s, there is no way Ford Engineers could have known how well every ground path in their EEC IV designs would hold up after thirty years. I decided I would try to enhance their original design.

I took a 12 ft. long battery Jumper Cable (available at RockAuto.com!) and clamped one end to the engine ground near the battery, then with the ignition key on and the car in its broken state, I started clamping the other end of the cable to metal points all over the car while listening for the fuel pump to start up. I had some inconsistent false positives but finally found the sweet spot when I clamped the ground wire onto the large Spare Tire Hold Down bolt in the trunk. With that bolt grounded, the engine/fuel pump stayed running indefinitely and always started up immediately. I am guessing my jumper cable was providing a new ground path for the nearby fuel pump. Maybe the fuel pump's ground path had changed over time, sucking the life out of the sensitive computer's ground path at the front of the car. I would probably have to get my doctorate in electrical engineering to know for sure.

The jumper cables running over the roof of the Ford looked tacky, so I ran some heavy gauge Primary Wire I had on hand from the main engine ground to a new bolt on the firewall and then I ran more wire from the engine ground to three separate new bolts mounted near the spare tire well in the trunk. There was an unused hole and grommet in the right front door jam so the new cable installation is professional-looking and out of sight. All the heavy wire might have been overkill, but I wanted to make sure I did not inadvertently burn up a too-thin wire, and I wanted to be sure that both the computer at the front of the car and the fuel pump at the rear of the car had excellent, independent ground paths.

Tom Taylor,
RockAuto.com

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If I may add my 2 cents worth...... IMPEDANCE, or a "high impedance ground" is really only relevant to an alternating current circuit.  True, some of the electrical devices in a vehicle use an alternating current in their communications and polling protocol and impedance in those situations may be relevant to proper operation - but, generally, no.  Vehicles are routinely powered by direct current as are their peripheral devices.  The good and the bad of this is the commonly encountered problem of creating "ground loops" in AC systems is not of great concern in DC derived power systems.  So, possibly in the name of saving cable and a few pennies the vehicle frame is often used as a DC ground point from the back to the front of the vehicle.  All of the vehicle's metal body is suppose to be bonded to the frame (if a frame does exist) which in turn is bonded to the engine and vehicle battery.  I would bet a doughnut to a dollar that the referenced fuel pump motor was simply grounded to a tab on the tank which in turn is grounded to the frame which is then grounded to ???? before the engine.......... Unfortunately, electrical ground connections made to the vehicle body over time may develop a high resistance at the connection point that adds strictly an ohmmatic value to the needed 2-wire circuit.  When a device ground connection is dependent upon a bridge to yet another body ground connection which is dependent on even another body ground connection and so on, any added resistance in this pathway will result in the intermittent or non-operation of that device.  This is what brings out the crazies for anyone attempting to trouble shoot a vehicle problem that includes a "bad ground". 

Fortunately, the fix is often simple -  add a new ground wire directly from the existing device ground wire connection of the same (or larger) AWG and run it directly to the vehicle engine and battery negative.  Yea, you've gotta find a way to run the wire which often presents a problem.  Also, on a vehicle be absolutely sure you are using pure copper marine grade wire and not some lower grade aluminum wire with a copper outer coating graded according to foreign standards.  Junk wire like this abounds, is cheap, and is often unknowingly used.  This will relieve many headaches, future problems and most likely fix some other issues you didn't even know you had.  Proactively adding ground home runs to devices or specific frame areas is never a bad idea either.  Unlike AC systems, you can have as many grounds as your heart desires in DC systems.  Over the years, I've collected some decent checks from area auto repair and RV shops that have devoted hours trying to resolve what turns out to be a bad ground issue after their wasting hours in tech time and parts to find themselves back where they started.  The strange thing is the solution(s) are not rocket science, yet they are repeatedly overlooked.  BTW - I like the jumper cables running over the cab of the Ford truck.  Not a permanent solution - but heading in the right direction.

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Back when Spot was a pup, we had several IH trucks on the farm.  They all had one thing in common, poor starter performance.  IH had used a very short braided ground strap from the battery to the firewall as the only ground on the vehicle.  We added a couple big gauge ground wires to the block, frame, etc., and everything from radio to headlights worked better.

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2 hours ago, rickeieio said:

Back when Spot was a pup, we had several IH trucks on the farm.  They all had one thing in common, poor starter performance.  IH had used a very short braided ground strap from the battery to the firewall as the only ground on the vehicle.  We added a couple big gauge ground wires to the block, frame, etc., and everything from radio to headlights worked better.

I was thinking as my truck ages, I could add some new ground straps at strategic locations to improve ground.

This is what brought me to read the entire original story, and share it with the group. 

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3 hours ago, rickeieio said:

 We added a couple big gauge ground wires to the block, frame, etc., and everything from radio to headlights worked better.

But the engineering group lost to the marketing group in the company softball game, thus everything had to be built to sell at a particular price point. Anything that drove up the expenses was deleted from the build line, radio block off plates became fashionable, lighting became an (extra) option. 

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I still have the sun visor, which had the "line setting ticket" for the '59 B-180.  Right arm rest was optional, right sun visor was too. Yes, it was a beast, with a BD-308, 5 speed and a 2 spd. axle.

The good old days is now.

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We smoked a lot of single wire AC clutches back in the 90's.  It took them forever to get them changed to 2-wire.  The switched ground, but single wire case grounded oil pressure and water temp warning switches used to throw me for a loop as well.  Spent many long nights trying to get that beeper to go away.  30 years later that beeper is still in my head.

In my teens and 20's Dad got me a 2nd harvest job where they started right as we were done.  100 bushel dryland, no more russian thistles, no more deep furrows, goodbye farmer pipes, we got wheel tractors, McDonalds, and close to girls in town.  Fat city and I ought to have the best wheat truck made out there in the "real Palouse".  Get there on the first day and my two trucks a pink colored '48 something -or-other International and a '59 B-180.  Uggggh....Seriously cramping my style!  The '48 and I got along with pretty good long as the vice grips stayed on the 2-speed lever thingy.  But that B180 I freakin hated that truck and it hated me.  I've disliked a few trucks, got along with a few others cuz I had to, but that one I just had genuine hatred.  It never would die though, fact I don't remember it ever breaking down.  Had to deal with it for 10 some years.  I lost track of it nowadays but it is probably still out there doing something.

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On 2/24/2020 at 11:16 AM, rickeieio said:

 (snip)  We added a couple big gauge ground wires to the block, frame, etc., and everything from radio to headlights worked better.

Sometimes being a "senior" means our stories impress youngsters as boring and irrelevant to current technology.  Still, there is much to be learned from our old dumb luck and experience (right Scrap?).  Some decades back I spent untold hours installing General Electric Progress Line radios in emergency vehicles.  If one simply dropped the radio in and connected power it was a given that the amount of noise accompanying the radio signal generated by the vehicle would be significant.  Of course, the first item we added if not already present were resistor plugs and wires, additional component condensers, some shielding and ALWAYS multiple ground straps between body components.  IMHO, not much has changed with unibodies, alternators, electronic ignition, noise blanking circuits, etc.  The grounds on new vehicles are marginally better but are still a source of RFI and faults in electronic components. The approach given by rickeieio is still a necessary solution if you want to avoid those phantom electrical issues that can cost hundreds to thousands of dollars as today's techs throw components at a vehicle in hopes of solving a issue - only to have it return in short order.

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I could have gone all day without being reminded, I'm a senior......

There's a member here who had issues with the landing gear on his rv.  In the end, the grounding cable from battery to chassis was undersized for the load.  I believe Randy figured that one out.  And he's even more senior than I.

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