Update on ZF trouble 87FC35

[Jeff Miller]

First, I am just getting caught-up on this problem, so bear with me
if I've showed up in the middle of the movie.

If the coach won't start with the ignition key, look at that problem
first. If the ignition switch isn't getting proper power then the ZF
probably won't either.

The ZF has a relay box, a flat aluminum box, has three connectors
plugged into it. I have a spare (new) one here, but since it is
simply a few Bosch relays on a circuit board inside, easy to repair
if it is the problem. This box supplies power to the ZF.

There are two wiring diagrams for the '87 FC/ZF, 1255157 inactive 3-
17-87 and 1314327 the later one. The early one ('157) has three
connectors on the relay box: 11pin/4pin/8pin. We'll start with this
early one. The power comes from: a red wire from the ignition switch;
a white/green wire from the ignition terminal of the terminal switch
above the main batteries; and a 20a ignition-hot circuit breaker.

The later version ('327) is powered similarly with the addition of an
orange wire off of an 8a ignition-hot circuit breaker, this relay box
has three connectors also but they are 13pin/4pin/8pin.

With the ignition on, check the voltage and check with a light also:
the body-hot terminal and ignition terminal on the battery-
compartment terminal switch, then with the grille and left
wiper/access panel open check all of the load-side terminals on all
of the circuit-breakers behind that panel. You might also pull the
small panel out of the dash (first) with the ignition switch to see
if there is proper power to/from the ignition switch, changing that
switch in an '87-'89 FC is a 5minute job at worst.

Good luck, hope I gave you some useful info, not just more confusion.
BTW the master wiring, chassis drawing for your coach should be
1284967.

If all is lost, I'm currently 'Birdless and accepting donations, will
take it off of your hands ;~)

- Jeff Miller
in Holland, MI


--- 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
>