No go on any speed of the fan on vent setting. Following steps in service manual, blower motor-ok, relay-ok. So now I'm at the pinpoint test of: Measure voltage between A/C-heater function selector switch connector pin C204-4 and ground.

So question is: Is there access to checking this connector without having to pull off the center controls panel on the dash to get to the connector on the back of that switch?

 

Checked voltage between A/C-heater function selector switch connector Pin C204-4, Cicuit 489 (PK/BK) and ground. No voltage. But if I run a test lead (+) from battery to that pin, the blower comes on. So problem seems to be the wire leading to that connector pin is shorted out somewhere.

I can't see any breaks shorts in the wire along the harness that I can see. Where is that wire coming from? Workaround solutions?

 

You'll have to tear into the dash in order to access the connector(s) behind the Function Control electro-vacuum switch (Heat, A/C, Vent, Off, Mix etc) and the fan speed control switch. Sorry to say this is the only way to see that part of the wiring.

Its highly likely the fan speed control switch or its chassis wiring connector have melted and lost continuity. This is somewhat common, replacement parts almost always available through NAPA.

 

Thanks, JWA. You are right. I did have to pull out the panel. Wasn't as bad as I thought. The results are in my second post above. The connector wasn't melted though. So, do you think it's the wire from that pin that is shorted somewhere back from the connector?

Wish I had a wiring diagram.

 

Where are you getting the pinpoint test steps? Those are typically in the service manual which would be paired with a schematic of that circuit.

Since your year van isn't posted I don't know where connector C204 is physically located.

You can also go to AutoZone.com for their free online schematics free to view and/or download/print as needed. You have to "register" first but that's relatively painless.

If you'll be doing this sort of work often I'd strongly suggest an EVTM for your year----they're invaluable for such troubleshooting.

Sorry can't be more directly helpful--also sorry for missing your initial test results and repeating your findings.

 

Again, Thank You very much for helping, JWA. My van is a 1999 E350 12 Pass. SuperDuty. I'll see if I can post a couple pics.









This is the Pin in question. A pink and black wire. If I run a + test lead from battery to here (where pencil is), the blower works, even AC can be switched on! But from here I have no idea where to go .

 

I'm reading from an EVTM for 2000 E-Series, should be close enough to your van. Before we dig too deeply into physically tracking individual wires make sure the electric side of the Function Selector Switch (Vent, Defrost, Heat, Off etc) has continuity in all positions except Off. I don't have a pin out drawing for C204 however when you're adding power from the battery to the Pink/Black terminal of that connector you're showing the possible short or blown fuse is before the Function Selector Switch.

That Pink/Black wire is the power feed into that connector. Following the EVTM (cell 54-1) you'll see its fuse protected 15 amp at the Central Junction Box (CJB, inside cabin fuse panel), fuse #13. Leading out of the CJB via splice connector S203 the Pink/Black wire splits into two feeds, one leading to your C204 connector and one leading to connector C237, pin 7 feeding the blend door drive circuit.

Backing up to connector C204 there is a Yellow/Red wire leading through several connectors (in line and splice) eventually leading to the Blower Motor Relay located in the Battery Junction Box (BJB), aka underhood fuse/relay box.

You should have power through to pin #86 on the Blower Motor Relay which is one side of the holding coil for that relay. Pin #30 of the BMR should be powered at all times, fuse protected by a 50 amp fuse located in the BJB.

Not sure how extensive your workshop manual is relating to electrical schematics but if this sort of DIY is common to you think on investing in one of those, typically found and quite afford through eBay. If all this above isn't helpful PM and we'll talk via phone, possibly Monday 9/28.

Update: EVTM for 1997 E-Series shows a Component testing procedure for the Function Selector Switch in cell 149-5 but it seems my EVTM for 2000 has a misprint that leaves out this step/drawing. On cell 54-1 of your EVTM looking at the schematic for the FSS on the right hand side of the switch block drawing there should be a reference to switch testing procedure, page/cell number listed. Follow along in cells beginning #149 for Component Testing: Function Selector Switch.

Anyway hope some of this helps!

 

Well, this is unbelievable. After checking backwards for power feed from the function switch connector, everything came back to the fuse block. Hoping to find something different, which is the definition of insanity, I pulled that circuit's fuse again. It was clearly blown! Yes, fuse #13. The first thing I checked before jumping in to this head first. No question it was the right fuse that first time I checked. I have no explanation how this is possible, to see that fuse intact and then wide open a couple days after fooling with everything else. Or, maybe I have gone crazy...

Very, very big thanks to JWA for sticking this out with me to the end. When in California-Steak dinner on me.

Note: That EVTM is a separate publication from my workshop manual. I don't have it, but will likely order one now!

 

Visual inspecting a fuse can be very misleading----some develop an open element that's not an over amperage condition---its happened more than once to most of us I'm sure. Find and use a dedicated automotive-type continuity test light----I'm using an older Snap On model I bought in the mid 80's. These don't need to be elaborate, uber sophisticated---just something to indicate if voltage is present between any one point and ground.

As another general rule anytime an electrical device stops working first check should be its fuse or connection to power. Test light, not "looks fine to me....."

Here's an EVTM I'd strongly suggest ASAP: http://www.ebay.com/itm/361389505136?_trksid=p2060353.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT
As luck would have it just a few days before your post I found a NICE '99 EVTM for $5, using it to round out my collection of EVTM's from '97 to 2014.

Steak schmeat----would like good seafood instead!

Glad we could help.

 

Got it!

And seafood it is-actually my preference also.

 

Cool deal then-------I'll call when in town, just not this weekend!

 

Sorry to have to report, but the problem seems to go beyond a fuse issue. Fuse #13 in the interior panel keeps blowing. It held for a long time while the function control panel was hanging out, but after buttoning it back up the fuse blows after a few minutes while driving. So much for the easy. Could it be the switch?

 

Had to re-read everything here---forgot all about this problem, thought it was fixed.

The Function Control and/or the blower motor switch AND their chassis wiring connectors could be at fault. If there's any signs of discoloration of the connector shell bodies or the wiring insulation you've had an over-current situation which may have caused high resistance in a circuit leading to the delay in fuse opening or blowing.

I don't see any evidence of this in your photo but even so careful inspection of that wiring and connectors might reveal something. Another though is have you or a previous owner connected any other device to the Fuse 13 circuit? Normally that 15 amp fuse runs for years without opening assuming the blower motor is in good working order.

OTOH the blower switch have been known to get very hot and melt ever so slightly yet not open that fuse. Odd situation but just saying its not impossible.

Let us know how this works out------you should be close to 100% success by now.

 

I put in a new function selector switch. I was encouraged after driving around for half an hour with everything working but then the fuse blew again. Dang! Well, now I'm armed with my EVTM so I'll begin digging through that now to find the source of the short. Would there be any value in going through the pinpoint tests again?

 

Have you checked the resistor at the blower motor? My blower motor only worked on full speed. I pulled the switch and opened it, everything was ok inside out.
I then pulled the battery and the battery tray pulled the blower motor resistor only to find a nearly melted connector because of a completely rotten resistor. Ordered the Dorman fix kit with ne resistor and connector and have to fix that as soon as the parts get here.