Update on ZF trouble 87FC35

[Tom Warner]

Gregg you are absolutely correct in the hurt part but I am afraid of
"hurting" the ECU and advised Alan of that tonight. I understand that
a replacement is on the order of $6000...OUCH!. Thats totally insane.

If I had the schematics for the 1987 (I have a few of them but not
the ones Alan needs) that includes the wiring from the dash to the
ECU then I would troubleshoot the problem and correct it rather then
running new wires and bosch relays. I have advised Alan to order the
set of schematics for his specific coach from Earl Davis, about $85
and postage. In fact anyone on this forum that does not have the full
set of factory drawings for his specific coach should buy them. They
are an invaluable aid to keeping your coaches running.

As Alan found out he has at least one burned pin in one of the barrel
connectors that he had to wire around. I dont like to do that
preferring instead to replace the connector or the pins and keeping
everything original if possible. But as we know there are times when
a change is necessary for example installing Bosch 30 amp relays to
repower the headlights so they get full voltage.

Also I would encourage anyone that has a FC model to do the same with
the circuits for the A/C fans and the heat fans. That will get a lot
of the heavy current items out of the dash and eliminate the big
voltage drops. When I do that I also install relay sockets with
pigtails so in the future just have to unplug a bad relay and put in
a new one. I have been buying the Bosch 30 Amp relays for about
$1/each and the sockets for I believe $1.05 or so.

I think Ernies idea is a good one to check the push button
transmission selector to see if there is any corrosion in it. I
believe the transmission shifting problem and the starting problem are related.

Tom Warner
Vernon Center,NY
1985 PT 40

At 12:08 AM 9/14/2006, you wrote:
>Why find it. find a good hot lug and use a ignition wire to open a
>new relay to power the ECU. find out the amp limit and fuse it. Make
>a note on #19 of the change you made. You may have to power the
>relay that cuts off the starter solenoid as we now know that the
>starter solenoid wont power at all without power to the ecu. I know
>it sounds like ducttape and bailing wire advice but if you replace
>the relay supplying the power you may only be repairing a result and
>not a cause. It just sounds to me that fixing your failure will not
>correct the problem.
>
>I dont like to reengineere things. In my field of expertiese, I use a
>hammer. When that hammer wont complete the task, I get a bigger
>one. I think you need the expert advice of JohnF, TomW, CurtS JeffM
>and the other electrical members. This ZF power thing is gonna get
>some one hurt. It would be great to do an upgrade to a bus and keep
>it from developing the "ZF'up"
>
>Gregory O'Connor
>94ptRomolandCa
>
>
>--- In WanderlodgeForum@yahoogroups.com, "Alan"
>wrote:
> >
> > One more thought. I re-looked at the "fix" on the web site for a
> > low-voltage problem. I don't think i've ever found that 12 volt
> > relay for the ZF. I found the 75amp one, but this appears to be
> > another one. ZF wire #19 is nearly impossible to trace. best i
>can
> > tell, it goes under the coach and off into oblivion. ...But my
> > common sense tells me I'm missing that relay and it's probably
> > someplace accessible, I just don't know which one it is. ANY IDEAS
> > ON WHERE THIS RELAY IS?? I'm betting at least 50/50 this is still
> > my problem.
> >
> > Ernie, mine has the push-button gear selector.
> >
> > Bill, your suggestion about checking the barrel connectors was good
> > too. I had a problem there too. I'm not sure how these problems
> > are related, but probably somehow. I had a melted pin in one of
>the
> > connectors. It was the 12v supply to the ignition switch. I'm
> > suspecting it had been going bad with corrosion, and somehow all
> > my "trouble shooting" was the end of it. I corrected that problem.
> >
> > Thank,
> > Alan
> >
> >
> > --- In WanderlodgeForum@yahoogroups.com, "Alan"
> > wrote:
> > >
> > > Well, after many hours this is where I currently am.
> > >
> > > 1. I have zero volts going to my ZF ECU.
> > > 2. The coach won't start. Now I'm pretty sure that's because
> > > without voltage to my ECU, the coach doesn't know if it's in gear
> > or
> > > not. (I can jump my starter solenoid and it starts.)
> > > 3. I talked to Dan at ZF in Chicago and he was quite helpful. He
> > > told me how to check voltage on the ZF. BUT he didn't know where
> > the
> > > ZF gets it's power off the coach.
> > > 4. I am getting volts out of my 75amp ignition relay with the key
> > > turned on.
> > >
> > > There are bunches of ZF wires behind the grill in the steering
> > > column access panel. There are also two silver boxes with what
> > are
> > > apparently ZF wires going in and out of them. The boxes are
>about
> > > 4" x 4" x 1". However, I know these aren't the ZF ECU. It is
> > > located underneath the push-button gear selectors by the driver.
>I
> > > don't know if they have anything to do with power.
> > >
> > > Questions (If anyone knows):
> > > 1. Where/how does the ZF get power from the coach?
> > > 2. Does the power go through the filtered power source under the
> > > couch?
> > > 3. What would keep me from getting any power to the ECU?
> > >
> > > Tomorrow I'm ordering a full set of electronic drawings, but in
> > the
> > > mean time my neighbors would appreciate it if I can get the coach
> > > moved from the street.
> > >
> > > Thanks,
> > > Alan Johnson
> > > 972.769.2526
> > > 87FC35
> > >
> >
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