91' Bronco Electrical issue

[Kustom64Ford]

Hello there. I am in need of some help from fellow Bronco owners. I know that electrical issues are hard to diagnose without looking at stuff, but I thought I would throw this out there since the truck is dead in the water and I need to try and figure it out. First things first: The wiper motor died, at least I believe it is the motor and not the switch since the motor kept getting slower and slower until it stopped. Ok, so we drove off down the street, smoke started coming out from under the dash, right around the fuse box and wiper switch, and the truck died. Now it will turn over like crazy, but not start. I cannot hear the fuel pump pressure up now. The fuel pump is less than a year old. I checked all fuses and find nothing and I cannot see any burned wiring. I am thinking that the wiper motor possibly shorted something out? Is the wiper motor and fuel pump somehow on the same circuit? Or did something short in the ignition? I SUCK at electrical, but cannot afford to tow it somewhere and pay for fixing it. Any advice, help, suggestions are greatly appreciated.

[Steve83]

No better time than now to start learning! Do you have a Haynes & a digital multimeter (DMM)? Read this caption:



Find the wiper switch for your year & follow its power wire back to the fuse block, then see what ELSE is on that circuit and check to see if everything is still working. It's not hard to pull the fuse block down & spin it to check the wires on the back. You can check the ignition switch wires at the same time.

Does the CEL come on with the key in RUN? Did it before?

[Kustom64Ford]

Sorry, but I do not know what the CEL is? I believe all lights on the dash worked before. I haven't paid any attention to the dash lights since this happened.

I do have a manual, but recently moved and I cannot find it. I believe I have a DMM, but do not know how to use it. Like I said, electrical issues are my nemesis. I can do pretty much anything mechanical, but wiring makes me crazy!

[DLuders]

CEL = Check Engine Light. This YouTube video below shows how to do a 1984-1994 Ford Self-Diagnostic Test, and get the test codes:

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There is a "Pulling Codes" video at the bottom of this BroncoDriver.com webpage, and there is a link to the engine warning light Codes Chart PDF document. Note that if your Bronco is 1992 or before, it will have 2 digit codes; 1993-96 uses 3 digit codes.

[Kustom64Ford]

My Daughter miraculously found my manual. I do not believe the CEL is on. I can try to pull codes, but not sure what I am going to get if I have some burned wiring? I will go see what I can find.

[SamsRX7]

Make sure that you don't have a Radio Shack car alarm with the ignition kill on it. I have removed several of those for people.

[Steve83]

Originally Posted by Kustom64Ford

...not sure what I am going to get if I have some burned wiring?

You'll get A RESULT. If the CEL never comes on, that tells you something. If the code is PASS, that tells you something. If you get fault codes, they tell you something. This caption also explains the process:



If you can't find the manual for your DMM, download the manual for any DMM; they all work essentially the same. Then start messing with it. Get some old dry-cell &/or watch batteries, and practice measuring DCVolts. Then set it for resistance/Ohms/continuity, and practice measuring metal objects, rust, wet dirt, your skin across various distances, an orange, scraps of wire from the truck, points on the steel body/dash/engine/frame...

[Kustom64Ford]

This is where I am at right now. I pulled the fuse box best I could. There are no burned wires that are visible. There are no burned fuses. Everything in the truck works (accept the wipers) and of course it will not start. I see no burned wires from the ignition switch. So, the only thing I can see not working is the fuel pump. I also replaced the fuel pump relay because I had a spare and thought that might be it. There is no car alarm on the Bronco. I will take a jumper wire and see if I get any codes.

[Kustom64Ford]

So, check engine light does not come on, and I cannot pull any codes. I jumped the fuel pump and it works fine. Not sure if it is a no no, but I left the fuel pump run on the jumper and tried to start the truck, but still would not start. So, now I know it is not a fuel problem, other than the pump not pressuring up when turned on. I am no expert, but I am thinking ignition or fusible link? I have not been able to locate a fusible link yet though?

[Alvin in AZ]

Originally Posted by Kustom64Ford

This is where I am at right now. I pulled the fuse box best I could. There are
no burned wires that are visible. There are no burned fuses. Everything in
the truck works (accept the wipers) and of course it will not start. I see no
burned wires from the ignition switch. So, the only thing I can see not
working is the fuel pump. I also replaced the fuel pump relay because I had a
spare and thought that might be it. There is no car alarm on the Bronco. I will
take a jumper wire and see if I get any codes.

So, check engine light does not come on, and I cannot pull any codes. I
jumped the fuel pump and it works fine. Not sure if it is a no no, but I left the
fuel pump run on the jumper and tried to start the truck, but still would not
start. So, now I know it is not a fuel problem, other than the pump not
pressuring up when turned on. I am no expert, but I am thinking ignition or
fusible link? I have not been able to locate a fusible link yet though?

You are kicking serious electrical butt! ...you just don't know it. ;)

Keep going, the trouble is right there waiting to be found because it hasn't
gone and cleared itself up on you. That's your only "fear" at this point, that
the trouble will clear up before you find the problem. BTDT a jillion times. :)

The meter will lead you right-to-the-trouble if you "let it".

That's all you need to learn about electrical troubleshooting is -how- to let
the meter find the trouble. This hands-on-trouble you got going right now
will do that for you.

Wiring diagrams, a volt/ohm meter and the willingness to "stand on your
head" when needed is all you need to make it happen.

-resistance-
Steve's idea to read resistances (ohms) on a bunch of crazy-ass stuff is
genius! :) Do some of that, get a feel for it.

-voltage-
Read the Bronco's battery voltage.

-voltage drop-
That one is trickier in that it takes more explanation is all. Not sure at what
point you're gonna need to use that one today (or not) but it's an important
one for future electrical troubleshooting.

(example)
While the wiper switch is "on" (wipers working or not) you read the voltage
(any voltage) across the contacts of the wiper switch. Any voltage reading
you get is the -voltage drop-.

Zero to full battery voltage is possible.

Zero volts is best of course, if the wipers are moving back and forth. ;)

-short- and -open-
If you were to get "full battery voltage" across the contacts then the
contacts aren't making good, they are -open-. The rest of the circuit is
less-resistant than the contacts. In-theory the rest of the circuit is fine.

Fix the switch's contact problem (or bridge it with a wire) to test the
"theory". If it still don't work (and the wire ain't getting hot as heck;)
continue on reading voltage drops.

That's one way to do it, another is to use the ohmmeter hooked in series
with the circuit.

A -short- circuit is the sort of thing that makes wires smell like they're
burning. An -open- circuit is like when you turn a wiper switch off. The
circuit is -open-. But also if the contact inside the switch is bad or a loose
wire that keeps the circuit from working. If that loose wire were to touch
something it could cause a -short- circuit and burn some wires up. :/

-series- and -parallel-
When you read the voltage on the battery the voltmeter is in -parallel-.
If you >disconnect< the battery cable and put one meter lead on the
terminal and the other on the cable clamp the meter is in -series-.

Typically you use ampmeters (with the circuit energized) and ohmmeters
(with the circuit de!-energized) in series.

-------------------------------

Wiring and hunting down wiring problems "hurts" sometimes. :)

Reaching into places that wasn't meant to be reached into by your fingers,
hand, arm, shoulder, chest, waist, hips while standing on something rickety
or hooks jammed into a pole or in this case upside down "standing on your
head" while working under a car-dash (or relay house at work).

A couple guys at work would have made good wiremen but they were just
too short and stubby. LOL :)

Alvin in AZ

[DLuders]

@ Kustom64Ford: My son has a 1989 Ford Bronco XLT (the same 4th-generation Bronco as your 1991). I just scanned the entire Section 35-60 of the 1989 Ford Bronco Truck Shop Manual ("Windshield Wipers - Electric"), and placed the 20 pages of scans on this Flickr photoset: http://www.flickr.com/photos/4298857...628659/detail/ . You can left-click on each Flickr image to select it, right-click on it to see the original (largest) size, and read it or print it on your computer.

You should look closely at the electrical schematics to find out what is preventing a complete circuit. If you cannot find the problem even with these Truck Manual pages, print them out and give them to your mechanic -- they will save him time and you money.

[Kustom64Ford]

Thanks guys for the input and Alvin, I will have to read and re-read that to make sense to me, but thank you for taking the time to explain that. The wipers are the least of my concerns right now, because I am pretty confident that it just needs a motor. The truck not starting is my major concern. I am not sure that the 2 are related? I will try to figure out how to use my DMM. Not sure if it is digital though. I did not buy it, I inherited it, so no manual. I will try to play with it a bit and see if I can figure it out. Thanks again.

[Alvin in AZ]

Originally Posted by Kustom64Ford

Thanks guys for the input and Alvin, I will have to read and re-read that
to make sense to me, but thank you for taking the time to explain that.

The truck not starting is my major concern.
I am not sure that the 2 are related?

I will try to figure out how to use my DMM. Not sure if it is digital though.
I did not buy it, I inherited it, so no manual.
I will try to play with it a bit and see if I can figure it out.

Thanks for that and to DLuders for scanning the manual, heck it was like
"hard work" just down loading that baby. LOL :)

As far as the meter goes it's sounding better all the time, it's prob'ly not
a stinkin' digital "DDM" (damn digital meter). If it's an analog meter (with
needle and scales) you've got a leg up on the DDM users. Those things
suck for troubleshooting. No kidding. :) Been argued over the Internet
a bunch of times with the DDM guys having to back-up every time. ;)

The same process used to find the trouble with the wiper is used on any
other electrical trouble. But some things are better using past experience.
Like changing out a light bulb instead of breaking out the meter and wiring
diagrams.

But verifying the circuit voltages feeding the TFI for example, sure as heck
won't hurt nuthin'. ;)

Alvin in AZ

[Steve83]

Originally Posted by Kustom64Ford

...check engine light does not come on, and I cannot pull any codes. I jumped the fuel pump and it works fine. ...I left the fuel pump run on the jumper and tried to start the truck, but still would not start.

The EEC isn't powering up. Click this, read the caption, then read the NEXT few:

Originally Posted by Kustom64Ford

I will try to figure out how to use my DMM. Not sure if it is digital though.

All DMMs are digital; that's what the "D" stands for. If it has a needle, it's analog (just a "meter", or "multimeter" if there are several scales); if it has an LCD display, it's digital.

Digital is vastly superior because it puts LESS load on the circuit being tested, and therefore, has less practical error and does less damage. Digitals are also inherently more-accurate because their logic chips are more precise than the winding of an analog needle & a clocksping, and over a MUCH wider range.

[Kustom64Ford]

HMM. EEC Power Relay possibly? Sounds like it certainly could be the problem. Relays are cheap, so worth a try. Thanks guys.

Is this relay known as anything else? Trying to track one down and haven't any luck.

[DLuders]

EEC = Electronic Engine Control module (circled in red in photo below):

[DLuders]

Here is a 4-page procedure for conducting a "Ford EEC Power Relay Test" -- http://easyautodiagnostics.com/ford/...er_relay_1.php . You can find some for sale on this PartsGeek.com webpage .

[Steve83]

Originally Posted by Kustom64Ford

Is this relay known as anything else? Trying to track one down and haven't any luck.

Didn't you read those captions & follow the links in them? They're known as Bosch/Tyco/ISO relays, and they're available ANYWHERE. I prefer the ones in junkyards because they're OE-quality at garage-sale prices.

Originally Posted by DLuders

EEC = Electronic Engine Control module (circled in red in photo below)

That's certainly NOT the EEC. The EEC is hidden behind the cruise servo in that pic, at the lower R. The circle is the EEC PWR and FP relays, but you don't test old-style relays; you replace them with new-style relays.

[Kustom64Ford]

I replaced the EEC Relay, and still nothing?? Guess I will have to wait for the next day off and do some more diagnosing. Why can't this sh*t be easy?

[Kustom64Ford]

Saw another guy on here with almost the exact same problem and it was the EEC. I will pick up a used one tomorrow. Hopefully that will do it.