'98 Expy with no high beams. Done all the idiot stuff I know of (fuses, lamps...) and I'm guessing the multi-function switch. How tough is this to tear into? Any suggestions?

 

I never opened up a turn signal, dont think I would even atempt, my only suggestion is take it to the dealer.

 

Verify that you have power at the MFS via the DB/O wire. Make sure it's seated properly in the connector. We've seen a rash of older trucks lately having issues with the pins not always being seated in the connector properly. Sometimes it's as simple as wiggling the wires. On your truck the high beams are fed from the same fuse as the headlights, so obviously I wouldn't suspect that. Does either the flash-to-pass or the regular high beams work? They're two different contacts inside the switch, so it's possible that, if both are dead, it may not be the switch...

-Joe

 

It is not hard at all to test the MFS, taking it to the dealer is paying way too much money to have someone run a simple test with a meter, don't let others try to scare you off it.

The steering wheel column can be removed, so you can get to the connectors.

The test procedure for the MFS :


You are looking at the first 2 test items.

I would actually take one step prior to this. Remove a bulb, and check if you have power at the bulb connector for the high beam, when the the MFS is away from the sterring wheel ( high beam position ). This will tell you if you have a bad MFS real quick, along with testing the Fuse and relay for the high beams. Line voltage for the low beams is directly through the MFS, unless you have DRL's

 

The fuse for the high beams is the same as the fuse for the low beams on his truck, so we can rule that out, and there is no relay. The high beams are fed direct from the fuse to the MFS to the light bulbs and high beam indicator via a wire that is independent from the headlight wire. If it was a bulb problem, the indicator would still light up. Power is being lost someplace between the fuse and the output of the MFS. That narrows it to the wire I mentioned above, the MFS connector/pins, and the MFS itself.

-Joe

 

Joe,

Forgot that '98s were still ine voltage via the MFS, both DRL and the high beam, my mistake on that one.

The common fuse to is the PDB fuse #8, 30 AMPs. This feeds the main headlamps switch, and the FTP feature.

The output of the FTP and high beams is via Fuse #16 20 A to the high beams and Fuses #26&28 to the low beams, so there are seperate fuses for the low and hi beams, after the MFS.

If you have voltage at the FTP position ( Dark Blue w/ Orange stripe ) that is only the FTP circuit #196, on the MFS pull back position.

Power to the main headlamp switch is via circuit #196 ( BD/O ) and if this was bad after the splice at the PDB, the low beams would also not work.

After the Main headlamp switch, circuit #15 ( Red w/ yellow stripe ) is what feeds the MFS.
The high beams ( with the main headlamp switch on, and the MFS pushed away from the steering wheel ) positon, the MFS feeds circuit #15 to Circuit 632, then to fuse # 16, then to circuit #12, and on to the high beams.

So the high beams run via 2 fuses and the MFS. I did not see a specific statement that Fuse #16 was checked, nor if the low beams actually work, or if the FTP function worked.

After your post, I looked in album #3, and I happen to have the 1998 EVTM 85-1.
This is where I verified the lack of Relay, after your post correcting me ( thanks ) , and the seperate fusing, and MFS function with circuit #196.



Guess I really should have started with a few more informational gathering type questions.
Q1. Do the low beams work ? ( confirms Fuse # 8 and the main headlamp switch along with fuses #26 & #28 )
Q2. Does the FTP function work ? ( one of the test items on the MFS test procedure just with the fuses and wiring included in the test - might be worth an end to end test considering lack of what does and does not work listed besides high beams )
Q3. Was fuse #16 in the junction box / relay panel checked ( fuses is a vauge diagnoses list ).

 

Aack! Now I get to wear the dunce cap..... I forgot about the secondary fuses between the MFS and the bulbs LOL!!

I was looking at the schematic right off the Ford server, so I was sure I wasn't mistaken.... I just didn't scroll down to the bottom half of the page. D'OH!!

I think we agree Fuse #16 would be the place to start. If he's got power at the PDB (which we can assume since it feeds the headlights) and no power at the bulbs, it's got to be a problem with teh MFS, secondary fuse, or the wiring somewhere on that circuit. I like to start with the simple stuff, so I'd go with F16.

 

No problem that is why we watch each other's back, to make sure the members get thing correct.

Fuse #16 is just about half way in the MFS to the bulb ( component wise, not distance ), so that is the most logical ( and thankfully easiest ) place to check for power in and out.

Stil think the questions confirming FTP and low beams functions should be answered, so we are not under the assumption that things are good.

 

There is no FTP, just low beams. I've checked the fuse as well. You've all shed much light on this, with much thanks from me.

With these answers, what do you think?

 

Check for power at fuse 16, check for power at the wires into and out of the MFS. If you have power into the MFS but not out with the switch in the FTP or high beam position, my money would be on either a bad conection or the MFS itself.

-Joe

 

Ok, with Fuse #16 looking good, try another test at that mid point.

Pull fuse #16 out
Turn main headlamp switch on
Push forward on the MFS ( turn on hi beams )
Using a volt meter check for +12 V ( to a known ground ) on both pins in the slot for Fuse #16.

This will tel you if power is coming out of the MFS to the fuse that supports the hi beams. This will confirm which way we should be looking, towards the MFS or towards the headlamps.

One other thing, and it might sound like a dumb question, you are looking in the pass compartment fuse block for this one, right ? Just thought I would clarify this.

 

No dumb questions. I've checked every circuit I can find, inside and out. Thanks for your insight and expertise.

 

And the result was ????

 

There's no need to check every circuit, just the contacts at fuse #16.

Almost sounds like we scared him off.... Makes me wonder if he read the whole post...