Electrical systems failing (No dash lights, 4x4, radio display, OD off and counting)

[eddie4.0]

I have a 1999 Explorer Eddie Bauer with the 4.0 SOHC motor.

I'm having one electrical system after another stop working. It started with the radio display going blank (radio still worked). Then the dash lights stopped working and then it spread to all the interior lights.

Now the 4x4 is off. The lights don't light up at startup for self-test, and turning the 4x4 switch does nothing. The OD on/off switch has also stopped working.

Here's what I've tried so far:
1. Bought a new dimmer switch - No effect
2. Checked all fuses - All are good
3. Looked for obvious wire breaks, bad connectors at the wire terminals - all look good
4. Disconnected negative battery terminal, and hooked up test light to positive terminal and ground - No obvious signs of a short
5. Connected multimeter to headlight and dimmer switch terminals and tested each circuit in connector:

• Infinite resistance in red/yellow wire from headlight switch to dimmer switch
• Infinite resistance in blue/orange wires on dimmer switch connector

I don't know where to go next with this. My Chilton's manual doesn't have a detailed enough wiring diagram to show me all the connections. Any help with this will be greatly appreciated!

 

[budwich]

Its a relay problem. Either battery saver or accessory delay... CHECK them with a meter.

 

[eddie4.0]

Thanks for the suggestion. Should I check the wiring to the relays or the relays themselves? When checking the relays, do I just connect my meter leads to the prongs of the relay?

 

[eddie4.0]

I have seven unmarked relays in the power distribution box, and no owner's manual to ID them. My Chilton's diagram doesn't match what I have, and doesn't list either of the relays you suggested. Are there other relay locations?

 

[budwich]

If in doubt, mark and pull all of them. First tests can be done with them removed looking at resistance / continuity measurements. In general, all the "combinations" should "agree".... ie. pin x to pin y should read the same on all relays that "look alike". Having said that no all the relays are the same pin wise... for what ever reason, Ford's "choice" of component dictated this. Most likely your problem lies with the accessory delay relay as it is the last in the circuit "chain" of relays.

If you are lucky, a search herein my find a post with pictures of the 99 relay module that you need to look for. Having said this, my references show the largest relay to be accessory delay.

 

[eddie4.0]

Well I checked the relays and they all read the same. The smaller relays had different readings then the three large relays, but each small relay read exactly the same and each large relay read the same too.

I went ahead and put in all new fuses since the previous owner had put in several fuses that were a lower rating then the circuit called for (7.5 in a 10, etc.).

So at this point:
All fuses are new
All relays check out
All switches work (replaced dimmer with a new one and no effect)

Also, after pulling the switches and then replacing them, 4x4 and OD are back online

The radio display is still out and the dash lights do not come on.

One more thing, my explorer has the autolamp feature. Could that affect the dash lights?

 

[96eb96]

Well I checked the relays and they all read the same. The smaller relays had different readings then the three large relays, but each small relay read exactly the same and each large relay read the same too.

I went ahead and put in all new fuses since the previous owner had put in several fuses that were a lower rating then the circuit called for (7.5 in a 10, etc.).

So at this point:
All fuses are new
All relays check out
All switches work (replaced dimmer with a new one and no effect)

Also, after pulling the switches and then replacing them, 4x4 and OD are back online

The radio display is still out and the dash lights do not come on.

One more thing, my explorer has the autolamp feature. Could that affect the dash lights?

Relays are correctly tested by applying 12 volts to the coil and seeing if they click and retract immediately, and check that the other end of the relay becomes and open circuit with a meter. Try this a few times. Look at the diagrams and see how the relays are wired. There is a coil and a dashed line. When the coil gets 12V, it pulls the dashed line and closes the switch. The battery saver relay in the first pic is grounded by the GEM module, the swich closes and the lights work. When the GEM wants to save power, it releases the ground and the switch opens. You get the idea.

The resistance test is only 1/2 the picture. Please restest those relays correctly. I had a nasty no-start once and I traced it back to an intermittant PCM relay.

Radio Backlight going black is a bad dimmer switch. Did you replace it with a new one? Can you test the dimmer switch (its not hard to do). I just went through this issue myself.

Here are some diagrams...they are very specific to a 99. Look at the second diagram and the take off from the dimmer switch... If you need any more info like harness pinouts PM me.

 

[96eb96]

Everything for completeness....

 

[budwich]

The auto lamps features has a relay in the same "set"... dimmer relay.... Anyways, although you did alot of stuff, I don't think you have quite got the source of your problem.... as I suspect your problems lie with the relay module. Reseating / moving things might have help but will likely come back / is still there.

PS. Your tests of the relays was good since without "documentation", it provides you with a sense of uniformity across units... some of which may be working while others might have been suspect. This leads me to believe that its not specifically a relay component issue but connectivity. From here / there, you then have to check for voltages at suspect relays both in terms of operating voltage on the field windings and across the switched contacts.

 

[eddie4.0]

Thanks for the diagrams. I will test the relays again.

I did notice another symptom that may narrow it down some. I discovered that the OD and 4x4 systems are actually working, the indicators lights just won't light when the headlights are on. If you turn the headlights off and turn on the 4x4 switch, the 4x4 light comes on. If you then turn the headlights on the 4x4 light in the dash goes off even though the 4x4 is still engaged.

Does this narrow the issue down at all?

 

[96eb96]

Thanks for the diagrams. I will test the relays again.

I did notice another symptom that may narrow it down some. I discovered that the OD and 4x4 systems are actually working, the indicators lights just won't light when the headlights are on. If you turn the headlights off and turn on the 4x4 switch, the 4x4 light comes on. If you then turn the headlights on the 4x4 light in the dash goes off even though the 4x4 is still engaged.

Does this narrow the issue down at all?

Either the park lamp relay or the headlight switch. What else can it be?

 

[eddie4.0]

Tested all the relays with 12 volts - no clicks
Then, I put in a new headlight switch - still no dash lights
Got a new parking lamp relay - still no dash lights
One by one, I swapped out all the relays with the new one - still no dash lights
In the process of testing, I noticed that the dash lights actually flash on for half a second and then go out - Any ideas?

I appreciate all the help you guys have given me. I wouldn't be this far without it. This electrical issue is driving me nuts!!

 

[budwich]

Not sure I understand your "Tested all the relays with 12 volts - no clicks".... what are you trying to say... that when you applied 12v across the operating coil of all relays, none of them operated????????

Anyways, your problem is most likely associated with the dimmer relay (in the relay module) get a meter and check to see if it has voltage (on T/W... ground on W/P) and operates and that the switched contacts are doing that... ie. switching voltage thru... from one contact (IN - R/Y or R/BK) to the other (out - BR/W) .... as taken from the previous posted schematics.

 

[96eb96]

Tested all the relays with 12 volts - no clicks
Then, I put in a new headlight switch - still no dash lights
Got a new parking lamp relay - still no dash lights
One by one, I swapped out all the relays with the new one - still no dash lights
In the process of testing, I noticed that the dash lights actually flash on for half a second and then go out - Any ideas?

I appreciate all the help you guys have given me. I wouldn't be this far without it. This electrical issue is driving me nuts!!

Hmm..you tested relays but did you test them across the coil terminals like Budwich said? That makes all the difference. Look at the 1-2 contacts on the relays in the diagram.

Maybe you have a bad harness. Sometimes you could have a wire that is just hangin' in...and it does not make good contact. But the fact that you see lights for a second could still implicate a relay, it could make contact then break...I had a problem similar to yours but it turned out to be internal to the dimmer module. I ended up tapping the dash to find it. My 96 is a bit different though..but you get the idea.

Try to wiggle the wires (move in all directions) that go into the harnesses and see if there is any change. A wiggle test is a troubleshooting step.

Another thing is to bring 12 Volts to points in the diagram. Look at the first wiring diagram.

Stick a pigtail wire in the harness and Try putting 12 V on pin 5 of the dimmer.

Then try pin 7. (rd/bk). If you put it on pin 7 and there are no lights there is most likely a break in the wiring. You can try this at other points too.

Look at the bright side...at least you don't have to work in single digit temps today .

 

[esupak]

Check all of your grounds for corrosion or if they are loose. I had a very similar problem one time and that was the problem.

 

[eddie4.0]

Well, since I'm working without an owner's manual, I tried to isolate exactly which relay is the parking lamp relay. I pulled all the relays one by one (Including 5 I found back by the jack storage), but the parking lamps still worked. Does the parking lamp relay control something else? Am I missing something?

Also, what exactly do you mean by applying 12 volts at the coil? I'm not sure I'm doing the testing right. Should I be keeping the relay in its spot and applying power somewhere, or be pulling the relay and running power to the contacts with it out of the truck? I have been pulling them out.

 

[budwich]

Well... based on the diagrams that have been posted by a kind person, I think that you have all the information that you need. "Simply follow the wires"... they will "tell" you which relay you are looking for. In terms of testing, "out of circuit" testing of a relay is the safest and is done by placing 12v across the operating coil of the relay to see if it does operate (click) and that indeed there is continuity across those contacts (again refer to the diagrams). From there, with the "newly tested" relay back in the circuit, use a meter on the appropriate wires to determine if the conditions exist for the relay to operate (12 volts and ground across the coil) and that the contact / wires are made when it does (ie. continuity / voltages appear on the "other side").

 

[eddie4.0]

Thank you for confirming the proper way to test the relays. It helps to know the right way to do it. I will do some more testing and let you know what I find.

Also, I just want to thank everyone for all their posts. Each post has been very helpful in helping me narrow down this problem.

 

[budwich]

To further expand mine and other people's comments.... look at the diagram that shows the dimmer relay. IF "proper" conditions (voltage and ground) are applied to the dimmer relay coil ( pins 1 and 2), then the relay will "click" ( switch) and the voltage appearing at pin 5 will now appear at pin 3. So the check would be to see if you have voltage at pin 5 in the first place and then do you have "proper conditions" on the coil (check for 12v and ground on 1 and 2) and then ultimately check if pin 3 has "received" the voltage as it should. Again use the diagram to find the right wire colors, then go to the relay module, find the corresponding wires which will then likely point to the right relay. Not exactly "good electrical science" but good enough when you don't have "all" the info about your particular vehicle.... OR ... maybe you do now ...

Finally, if the voltage appears at pin 3, does it make it "over" to your light switch?

Lastly, does your light on your light switch illuminate when the switch in NOT on? Does it go out when you turn you lights on with the light switch (ie. NOT using your auto lamps feature)?

 

[96eb96]

Eddie 4.0 is getting great experience here to troubleshoot problems like this in the future! Stuff like this is exactly what techs in a shop face every day. Everyone has to start somewhere...