Intermittent electrical issue, Please read CAREFULLY.

[billy14870]

Background info:

1998 Ford Ranger: 4.0; 4x4; 5-speed

Currently 291k miles, The problem started at around 275k miles.

I have spent countless hours on this one problem, I have taken it to three different shops and spend a fortune with no results.

The problem:

It seems like there is an intermittent interruption or some circuit, or short somewhere in the truck. When this occurs, it would appear that my PCM is loosing electrical power. The reason I think so is because I currently have a check engine light on for an un-related emissions code, when this failure occurs, the check engine light is NOT illuminated. Ill be driving down the road and all the sudden my truck will either die, or intermittently die resulting in a rough back and fourth jolt which can best be described as turning your key on and off really fast while driving down the road.

I know this is very difficult to follow, so I will upload a few videos to my youtube channel, and I will post the links below.

Please comment with any input you may have.

It will stop acting up out of nowhere and maybe be fine for another 4k miles, then out of nowhere start doing it again. One way that seems to make the problem go away is I finally get it to a repair shop, and the guy says hell look at it tomorrow. He called me back and says that the truck was running fine for 2 hours and he couldn't find a problem.

 

[billy14870]

More info

Also One of the last times I brought it to a shop, the day went like this.

I started my truck to let it warm up, as it was a cold day.

10 mins later I open up the driver door, sit in the drivers seat, and the engine immediately dies. There was no check engine light illuminated even though there should have been. I tried starting it and it just kept cranking. I then stepped out of the truck, and i saw the check engine light immediately come on, so I pushed in the clutch with my hand and started the truck. It fired right up. I sat in the seat, and it dies instantly, and the engine light was gone.


So I was tired of dicking around with this truck so I called a tow truck and had it towed to a shop. The mechanic thought that the issue would be under my drivers seat. So he pulled the seat, and lifted the carpet up. Under there, there are a few wiring harnesses that run through a hole in the floor pan. He found a few wires inside a hareness that were missing their insulation for some reason. He repaired those wires, and just like anyone else would imagine, I thought the problem was gone for good.

It just started doing its bullshit a few weeks ago. AGAIN. So I tare my interior apart for the both time to see what those wires went to that he fixed. It would appear that they go to the rear turn signals.

So that must have just been a coincidence that it seemed to have corrected the problem for so long.

I also am noticing a pattern between rain/damp conditions and the truck acting up.


Any input would be great.

Im thinking about replacing my entire wiring harness front to back.

 

[97RangerXLT]

Check all of your engine and body grounds. Sounds like you have a ground with a rusty contact

AJ

Sent from my Samsung Galaxy Note 4 while sitting in my underwear

 

[billy14870]

Bad ground?

The reason why I don't think its a bad ground is because no other problems occur when it happens. All of the lights, accessories, radio, ect still work.


I can best describe it as if you were to turn your key on and off VERY RAPIDLY while driving down the road.

 

[ginman]

Possible neutral safety switch issue... It should be up the clutch petal arm.

 

[Haywire6000]

Had kind of the same issue with my 1993. The issue was the fuse under the hood to the fuel pump. Every time I would hit a bump the cell would come on for a second and the truck would buck hard, it took me a month to find it. Could be the same issue just with the ECM fuse though....

 

[billy14870]

Fuse or relay?

Do you mean Fuse or relay?

 

[Tedybear]

Do you mean Fuse or relay?

Probably meant fuse.

If the truck has the power disty center box under the hood, at times they can get attacked by the "Green Goblins". That's where wiring starts to get green crusty build up and it creates a lot of electrical gremlins. If it's bump related, you can sometimes recreate the issue by tapping the box with a screwdriver handle.

Being that your truck is I believe OBD2. I'd be interested in pulling any codes, and freeze frame data. My wife's got a 01 VW Beetle that has an electrical gremlin (probably left over from WW2) Her's triggers the P0420 code. The rub? Look at freeze frame data for when the CEL triggered. The data recorded is all over the map and half of the sensors read max values.


Just sayin'...Might be time for a serious visual inspection of all grounds. (Each truck has a boat load of grounds scattered all over the body. Just because you have a working radio/heater...It can use a different ground then the fuel pump or engine computer....) Or a good old fashion Ford "Wiggle Test".

G/L with it!

S-

 

[Mark_88]

Had a similar issue but the truck lost all power to everything. This turned out to be green goblins in the main wire harness under the hood...it was an 88 with old clips that essentially fell apart in my hands when I tried to disconnect them.

I would also suggest going over every harness with a fine tooth wiggle test. If you get the truck running (check the inertia switch if this is still not running)...wiggle till it drops.

Wet weather and no starts are common Ford issues after a few hundred K so you might want to check the main power feed under the hood to start with...they can be corroded in the cables even if they appear to be clean. Check for minor breaks in the main power feed from the PDB to the starter circuit...I had issues with that one wire on my 98 engine (96 harness) that I eventually replaced outright and fixed a similar >>> no start >but> no crank...so not exactly the same if yours is cranking.

I would try spraying a bit of starter fluid in the TB to see if it fires up...that indicates fuel pump circuit...so narrows it down.

 

[Haywire6000]

I did mean fuse, sorry for the confusion.

 

[zekew64]

After thinking about this, I think that the EEC (or main computer) relay is what needs checked. The reason I say this is because you'll be driving, hit a bump, and the truck will "stutter" as though the key is turned off and on rapidly.

Also, the other clue is that when the truck is running, you have a CEL -- but when you have a no-start/no power/no crank condition, the CEL is gone. That means that the CEL isn't being tripped by the EEC to illuminate the check engine light.

I would check both voltage and continuity on all wires at the EEC relay at the underhood Power Distribution Box (should be black or brown). If you have any intermittent or non-existant voltage or continuity, check the wiring individually and see if it has been rubbed off or shorting to ground some way.

 

[OlBlue38]

START THE ENGINE USE A HANDLE OF A SCREW DRIVER ,TAP THE RELAYS AND SEE IF THE ENGINE DIES OR STUMBLES.Pull the fuse to the pcm, see if the terminals show any arcing. Also look at the terminals in the fuse box. Do the same checking to the PCM relay.

 

[ericbphoto]

I would definitely vote for a loose connection. Your descriptions indicate that movement or flexing of the truck (when you hit a bump, when you get in or out, etc.) is wiggling a loose connection and making or breaking its contact. It may be a ground. It may be a hot wire.

Try to connect the dots between what does or does not fail when it happens, in order to narrow down what circuits to look at. This may be very difficult without electrical diagrams, but there are some diagrams in the tech articles on this site that might help you.

One other thing. Is your ignition switch worn out? I've seen vehicles where people have driven them for years with heavy key rings dangling in the ignition switch and the assembly gets worn out so much that it causes problems.

 

[OlBlue38]

Sorry I did not finish my thoughts. If you are taping the pcm relay, and the engine stumbles or dies your problem will most likely be the PCM relay,especially if the yellow engine light does not come on. If this relay open circuits it is like turning off the ign switch. It probably will not even leave a code.

 

[Ranger4x4.0]

I had the exact same problem. Acually, everything you said is exactly what happened to my 1998 4.0 ohv 5 speed! From the check engine light problem thingy, which is just the computer trying desperately to guess the problem lol, to the horrible jerking that feels like the wheels lock for a split second. Everything I replaced, or "fixed" seemed like it was the magical solution for a month or so, but it is all coincidence. 1500 Flippin dollars later, it was the crankshaft sensor. $35 dollar part. Here is the link to my post http://www.therangerstation.com/forums/showthread.php?t=164134 And yes, mine done it worse in wet conditions, alot worse. Less oxygen in the air on damp days so the sensor signal loss will be more noticable, alot of small jerks.

Not saying it can be exactly it, but 99% sure. Don't hold me on it if it's not! Lol BUT, if it is, thank me l8r lol