Multiple Electrical Issues (GEM??)

[NeverBRich]

First off I am sorry if this is posted somewhere else. Been reading for hours on here in the last couple of weeks, to no avail.

So, the History. Bought a 1997 expy EB 5.4L around 5 yrs ago. I drove it for 2 yrs, It got an Exhaust leak, Manifold stud, etc etc. around same time rear controls for heater/AC stop working, as well as the factory radio. So I parked it outside for a year. then moved it inside for the last 2 yrs. Finally Saved a couple of dollars, ordered exhaust manifolds. Put everything back on. Fired it up. First click of key and it started. on to Rear Control panel/Actuator/blower.

Opened door all interior lights started flashing, started the truck they stopped. Power Locks, power Windows, radio and rear heat/AC now not working and I have flashing Interior lights to boot.

All symptoms except the flashing lights remain when started.

I have checked all the fuses, diodes, and relays, test light, Multi-meter, and battery.

Running out of Ideas.

Read somewhere that it could be the GEM. Also read on here to Stop attacking the fuse/GEM and tackle the individual problems.

Any guidance, schematics, suggestions would be appreciated.

forgot yes I do live above the 49th parallel so Snow, Rust, rain, and salt is all here.

(P.S. wife is threatening to send a shotgun shell and throw a match into it. I really like the Beast. Would hate to see it go up in flames)

 

[stamp11127]

Welcome to the site.

One main indication of issues with the GEM is a wet driver side floorboard or fuse box. What is the status of yours?

 

[NeverBRich]

The floorboard appears dry, carpet has no stains, the fuses and connectors appear fine, as in no corrosion or rust.

 

[stamp11127]

Doubt it is a gem issue but should be proven.

 

[NeverBRich]

OK upon testing all the LT Blue/Red I am getting a ground reading on all of them, According to the Schematic they should be live. So this Points in the direction of a bad Ground(s) or a short.

Any ideas on where to start hunting. all the obvious grounds(aka Blk wires are testing ground as well)

 

[stamp11127]

Depends on how you tested them. They do have a path to ground through each bulb.
Shorts on this circuit will usually blow fuses.

First step is to read source voltage at the battery posts (not clamps).

 

[NeverBRich]

By unplugging the plugs and back probing the plugs. Tested it with 2 types of test lights, one that is powered and shows ground or pos, and with the older version that has to be connected to either ground, or a Pos. I will Test it with the Multi-meter tomorrow

 

[NeverBRich]

Ok so Voltages.

Battery -------- 11.8v

Power Dis.t Box fuse 7 --- 11.7v
Tan/white Wire at Main Light Sw. ---11.7v
Blk./red at main light switch ---- 0v
junction fuse box fuse 18 ---- 4.6v
Dark blue/white ------- 4.6v

light blue/red

LF window --- 3.8v
LF door lock --- 3.2v
RT window --- 3.8v
RT door lock --- 3.2v
RT rear window --- 3.8v
LF rear window --- 3.8v
4wd mode switch --- 4.1v
function select sw. --- 7.3v
instrument panel --- 8v
rear control panel --- 0v checked with a live and got 7.3v so it is reading as a ground
rear defrost --- 0v " " "
LF rear vent Works
RT rear vent Works
front Blower Works
Rear Blower --- 0v (does not work) " " " "

Radio-----radio lights up, cd plays, no radio signal.


Anything else that you could lead me to test?
Or point me in a direction to check?

thanks for your time and help.

 

[stamp11127]

One thing I hammer into our students is always check your source voltage before troubleshooting an electrical problem so that you know the state of charge of the battery bank to avoid chasing g your tail. In your case the system voltage is way too low:

Open Circuit Voltage at the battery
100% = 12.6v
75% = 12.4v
50% = 12.2v
25% = 12.0v
dead =11.8 and lower

Your reading of 11.8v means the electrolyte activity is so low the battery can't do very much other than run some light electrical loads. If you have a battery charger I would charge it back to 100% then start troubleshooting.

Are all lights pulsing or just specific sets?

 

[NeverBRich]

All interior lights. currently Charging battery.