Sylan

Ok this post might be a bit long. You have been warned.

I'm in the process of restoring my '87 N/A to factory working condition. I bought the car with 87k miles and it run pretty good with a few minor issues. One of them being that my warning light cluster lights/buzzers work, but they dont all turn on when the key is in the ON posistion. May not be a big deal, but I want things to work properly. Oh yeah, and the clock stopped working recently with a known good light cluster

So far I have taken these steps to correct the issue.

*soldered the board on the cluster.
*bought a new cluster
*ran continuity and ground checks on the plug going into the cluster
*ran continuity and ground checks on the cpu
*replaced the cpu
*checked continuity and grounds on ECU
*pulled the intake manifold to clean ECU ground
*replaced alternator
*cleaned all grounds associated with battery/wiring harness
*lost mind
*kicked tires
*checked all fuses

The only thing that has gotten them to work(intermittently) was when i added coolant and put the cap on wrong. Drove to autozone and back, spewed coolant all over the right side of the engine bay. After i shut off the car and turned it back on, everything came back on as it was supposed to. When the engine bay dried up, they stopped lighting up with key on.

The only thing I could connect to this was the ECU ground(which was cleaned after), and 2 plugs right under the filler neck that were heavily corroded(from coolant cap housing having a leak.

I'm sure there were a few other things i've done to rectify the issue, but i can't think of them at this time.

On a side note, I've noticed that during the times the lights would come on with the key on, if i drove the car the shuttering on deceleration, or starting off in 1st gear ceased. As well the idle maintaned very steadily the whole time. Along with the 3800 rpm hesitation not happening.

Any possible suggestions on how to fix this problem? Oh, and yes I have searched the forums for a fix ^^see above attempts from forum suggestions.

If pics would help I can take some and post on request

satch

iTrader: (1)

Pull the two wire plug off the back of the alternator and ground the White/Black wire w/key to on and the idiot lights should light up. If they don't then either the alternator warning light relay, wiring or cold solder joints are to blame.

Sylan

grounded with a multimeter on 200k ohms and no change

satch

iTrader: (1)

At the largest plug of the CPU lies a Yellow/Blue wire and if this wire were grounded w/key to on then the idiot lights should turn on. If the W/B wire from the alternator were properly supplying the warning light relay in the CPU w/a ground then the relay should supply a ground on the Yellow/Blue wire that runs to the idiot lights. These lights already have a voltage signal to them and await a ground signal to light up.

MazdaSpeedDan

iTrader: (4)

Where at in Savannah? Me and a few guys can come over and check her out for you.

Sylan

back side of hunter, off chatham pkwy

can pm for address if you guys wanna make a day out of it, can have some beers and cook some burgers. Got a neighbor who owns an FD, but is too into his 3KGT to mess with it

HAILERS2

Like Satch said........it works just like the diagram in the FSM shows. The alternator when not turning puts a ground on the WHITE/black wire which in turn puts THAT ground on the alternarot relay inside the CPU. Relay pulls in and in turn puts a ground on the Y/L wire going to the warning light cluster to turn on ALL the warning lights. See attached jpg.

With key ON just put the White/Black wire to ground at the alternators small connector. You should be able to HEAR the alt relay in the CPU pull in doing this. Just a bare piece of wire from the alt case to the whtie/black will do it. No click means the alt relay in the CPU is kaput OR the solder connection on the Y/L wire on the CPU plug is ......a cold solder joint and needs repair. I'd gnd the Y/L with key ON to prove that first before repairing things.

OR a cold solder joint at the WARNING light cluster plug can cause the problem IF you actually hear the alt relay in the CPU pull in when the white/black is grounded to the alt case. Not unusual to have that problem at the warning light cluster plug.

Those lights in the warning are just looking for a good gnd on the Y/L wire coming from the CPU.

Above assumes the meter fuse and all other fuse are good.

RotaryEvolution

iTrader: (30)

call me debbie downer but i believe you just haven't been soldering the board properly.

the main power input to the idiot cluster controls most of it's function, if the clock isn't working then that is a pretty good indicator that the solder joints are bad or you lost power feed to the cluster. usually it is the cluster, i have never had a power feed issue on any car yet, but it is possible.

even simply plugging the cluster into another vehicle is not a good indicator that it is a good unit, pushing the plug a certain way usually results in temporary continuity/functionality.

always look for the easy things first, most of the time they are quick/easy things you are overlooking even if they do throw the stick in another direction.

Sylan

When i bought the new cluster and hooked it up, the clock worked for 3-4 days with no problem. Then just stopped, same thing with old unit's clock. every function of this cluster has worked at one point or another, just not at the same time. The old cluster was never re-soldered, the new one was soldered right before it was shipped to me.

RotaryEvolution

iTrader: (30)

never assume a new part is a good part, that is the #1 time waster of all time.

i wish it was legal to beat labor hours out of people who took parts of my life because their QC sucked ***. i might not be the ******* i am today.

Sylan

Well as previously stated, im leaning more towards Alt wiring at this point. The car is an S4 and had the S5 alt on it, so that set of wires was spliced to the new "plug" I've since re-spliced to the original plug. While I was doing all that, I found that the alt wires are not in the best of conditions, and the wiring harness between the alt and engine is in bad shape. That and having coolant spewed in that area has actually caused it to work. Not sure how that relates but yeah lol

RotaryEvolution

iTrader: (30)

a gentle breeze could also make it work, for a while.

MazdaSpeedDan

iTrader: (4)

Im up by Fort Stewart, Ill see if a couple guys can come down and help ya sometime next week or possibly next weekend, Ill be down there putting a FD together.

Sylan

Sounds like fun. It wouldn't be the FD that Carlos built the engine on would it?

MazdaSpeedDan

iTrader: (4)

Nope, This one is a shell up restoration and the engines being pulled from a rolled over FD that he owns as well. Hes going to just swap it in, no rebuild.