ZF Trans - Fixed - Low / No Power issue

[Alan]

Well, Thanks for help from all of you!! I finally got the coach
rolling again. I think my neighbors are going to throw a block party
to celebrate it not being on the street any more.

Here's what I fixed:

1. During this whole process I had the 12v wire in one of the barrel
connectors under the dash that had a meltdown. ...Not the wire, but
just inside the connector. I suspect it has probably had corrosion
issues for a while and somehow this problem finished it off.

2. My 12v power going into the ZF ECU was out. Initially it was
feeding 7.5v, but then it quit all together.

3. With 0v, coach would not start because it couldn't tell if it was
in gear or not.

4. I talked with Bennie at BB. We were never able to find where the
bosch relay is for this. My wiring is apparently differently than
everyone elses. Bob Janes called me this afternoon and gave me a
clue, however. Behind the access panel, behind the grill are two
aluminum boxes, about 4"x4"x1". They are not easily accessed and
not easily opened (but I'm going to open them later). Bob thought
the relays may be inside these boxes and I think he may be right.
Bennie at first thought they were flasher controllers. BUt there are
two many wires going in and I'm still missing a whole bunch of bosch
relays that should be there somewhere.

5. After more talks to Dan at ZF (again, very helpful) I cut the two
pink wires going INTO pin #19 on my ZF ECU. My ECU is behind a kick
panel, underneath the gear selectors.

6. I then connected the two wires going INTO pin #19 to a 12v
source. Coach would still not start and no power was going to the
gear selectors (they were not lit).

7. After talking again to Dan, we decided that one of the pink wires
may have been supplying 12v in and the other may have been taking
12v OUT to power gear selectors. At this point, I had cut those
wires in two and what I thought was the supply side originally, was
not connected to anything. (The other side of the cut went to the
ECU and I had hooked 12v to it.)

8. I decided to send 12v down each of the pink wires the other way.
In the end, I needed to send power down both of them and here's what
I think.
a. I think one of the wires supplied 12v to the ECU from a
relay. ALSO connected to that relay MUST be a wire that was
supposed to send power out for the neutral safety switch. It needed
power too. With that relay out, it was still not getting power
until I hooked it up at the other end.
b. The other wire sent power to the lights on the gear
selectors. When I hooked it to 12v, they came on.

So now, coach starts and transmission engages and operates smoothly
(better than it was before as it's now getting 12v).

Whew.. If any of that doesn't make sense, let me know. I want it to
be clearly documented for next poor guy with this problem.

Thanks,
Alan Johnson
972.333.4755
87FC35

[one_dusty_hoot]

!!O HAPPY DAYS!!,the neighbors can see the street, and...
best of all you're ROLLING AGAIN.

Quite a few of these ZF's in 87-89 FC's and later SP's also.
They seem to be a good transmission but when they are bad,
they are really BAD. With knowledge of them they may be an
easy to repair transmission, lot's of electrical. What scares
me is a $6,000 module that I've heard can go bad.

Glad you are up and running.
Bob Janes, 87FC35, Greenville, SC

--- In WanderlodgeForum@yahoogroups.com, "Alan"
wrote:
>
> Well, Thanks for help from all of you!! I finally got the coach
> rolling again. I think my neighbors are going to throw a block
party
> to celebrate it not being on the street any more.
>
> Here's what I fixed:
>
> 1. During this whole process I had the 12v wire in one of the
barrel
> connectors under the dash that had a meltdown. ...Not the wire,
but
> just inside the connector. I suspect it has probably had corrosion
> issues for a while and somehow this problem finished it off.
>
> 2. My 12v power going into the ZF ECU was out. Initially it was
> feeding 7.5v, but then it quit all together.
>
> 3. With 0v, coach would not start because it couldn't tell if it
was
> in gear or not.
>
> 4. I talked with Bennie at BB. We were never able to find where
the
> bosch relay is for this. My wiring is apparently differently than
> everyone elses. Bob Janes called me this afternoon and gave me a
> clue, however. Behind the access panel, behind the grill are two
> aluminum boxes, about 4"x4"x1". They are not easily accessed and
> not easily opened (but I'm going to open them later). Bob thought
> the relays may be inside these boxes and I think he may be right.
> Bennie at first thought they were flasher controllers. BUt there
are
> two many wires going in and I'm still missing a whole bunch of
bosch
> relays that should be there somewhere.
>
> 5. After more talks to Dan at ZF (again, very helpful) I cut the
two
> pink wires going INTO pin #19 on my ZF ECU. My ECU is behind a
kick
> panel, underneath the gear selectors.
>
> 6. I then connected the two wires going INTO pin #19 to a 12v
> source. Coach would still not start and no power was going to the
> gear selectors (they were not lit).
>
> 7. After talking again to Dan, we decided that one of the pink
wires
> may have been supplying 12v in and the other may have been taking
> 12v OUT to power gear selectors. At this point, I had cut those
> wires in two and what I thought was the supply side originally, was
> not connected to anything. (The other side of the cut went to the
> ECU and I had hooked 12v to it.)
>
> 8. I decided to send 12v down each of the pink wires the other
way.
> In the end, I needed to send power down both of them and here's
what
> I think.
> a. I think one of the wires supplied 12v to the ECU from a
> relay. ALSO connected to that relay MUST be a wire that was
> supposed to send power out for the neutral safety switch. It
needed
> power too. With that relay out, it was still not getting power
> until I hooked it up at the other end.
> b. The other wire sent power to the lights on the gear
> selectors. When I hooked it to 12v, they came on.
>
> So now, coach starts and transmission engages and operates smoothly
> (better than it was before as it's now getting 12v).
>
> Whew.. If any of that doesn't make sense, let me know. I want it
to
> be clearly documented for next poor guy with this problem.
>
> Thanks,
> Alan Johnson
> 972.333.4755
> 87FC35
>