1998 S10 - Wiring Issue from Instrument Cluster to Generator - Please Advise!

Hello Forums:

I have an S10 with 4.3L and a standard transmission.

The wiring harness attached to the right side of the manifold
seems to have an open. This wiring harness contains the 14ga
brown wire that is connected to the side of the generator.
A resistance measurement from the generator side of the brown
wire to ground shows 3K ohms.

A parasitic draw test shows that a short circuit is sending
60 ma of current through the 50A INT BAT fuse, located in the
fuse box under the hood. Removing the 50A fuse
decreases the current to approximately 40 ma.

Your advice on troubleshooting this situation would be most appreciated.

S10ner

Hello:

I am checking continuity of the wire that connects the instrument cluster
to the generator. A 14ga brown wire plugs into the generator via a plastic
connector.

The attached picture shows the connector to the instrument cluster.

Does the wire in slot A11, as indicated by the black line, connect to the
14ga brown wire? If not, then which wire/slot in the photo does connect
to this 14ga brown wire?

Thank you for your assistance.

S10ner

Hello Forums:

I have a 1998 S10 with 4.3L and a standard transmission.

A wiring harness attached to the right side of the manifold
seems to have an open circuit. This wiring harness contains
the 14ga brown wire that is connected to the side of the generator.
A resistance measurement from the generator side of the brown wire
to ground shows 3K ohms.

A parasitic draw test shows that a short circuit is sending
60 ma of current through the 50A INT BAT fuse, located in the
under hood fuse box. Removing the 50A fuse decreases the current
to approximately 40 ma.

Your advice on troubleshooting this situation would be most appreciated.

S10ner

Well you don't have a short or you would be blowing fuses. You need to continue with the parasitic draw testing to figure out what circuit is pulling the 40ma.

There are only two wires going to the alternator.......the large thick one that is bolted externally, and the other wire is used to turn on the BAT light in the instrument cluster......

That circuit is normally open.....it is grounded by the circuitry in the Alternator, when it wants to turn on the BAT light, due to an overcharge or undercharge condition........

As for your draw, 60 MA is not much...normally it should be 25-30 ma.....

A parasitic draw test shows that a short circuit is sending
60 ma of current through the 50A INT BAT fuse, located in the
under hood fuse box. Removing the 50A fuse decreases the current
to approximately 40 ma.

20 ma is only going through the 50A fuse, 40ma is going elsewhere...


Exactly what is your problem? These are very low draw currents....for example, if a glove box light was on, the draw would be 2500ma's.....is there anything aftermarket on the vehicle that has something like an LED light that might be lit?

Hello Forums:

I am looking for a pin-out diagram of the brown
C1 Connector that plugs into the Truck Body
Control Module.

I have not found a diagram online.

If someone can post a diagram of the C1 Connector
or a web address, this would be great.

Thanks,
S10ner

Exactly what is your problem?
It won't charge?
Battery runs down?

Merged discussion from Blazer Forum into this thread.

Hello Forums:

This vehicle would readily start some times and a jump was needed other times.

I disconnected the cables from the battery, the ground, and the generator
to clean the points of contact and to check the continuity of the cables.

A few minutes after I reconnected the 14ga brown wire to the side of the generator,
I noticed that the battery voltage was dropping like crazy. A coincidence? I pray that
the drop in voltage has nothing to do with connecting the 14ga brown wire.

A parasitic draw test shows that 60 ma of current are being drawn through
the 50A INT BAT fuse, located in the fuse box under the hood. Removing
the 50A fuse decreases the current to approximately 40 ma.

The schematic shows that the INT BAT fuse feeds five fuses located in the
fuse box on the driver's side of the dash. With the INT BAT fuse installed,
I removed each of these five fuses, which did not cause a drop in current.

I then pulled all the remaining fuses in the fuse box in the dash. Pulling neither
of these fuses caused a drop in the current.

Interestingly, pulling Fuse #4 caused the current to increase from 0.12A to 0.20A.
I guess that the current decreased from the 0.60A reading of the earlier draw test
due to the current drain.

I may be mistaken, but, I believe this current increase indicates an issue in the
circuit fed by Fuse #4. The schematic shows that Fuse #4 feeds the instrument
cluster and the TBCM.

The next step is to check the continuity of the wiring from Fuse #4 to these
two components.

Please offer any suggestions for troubleshooting or for things to check.

S10ner

A 60 mA draw on the battery would not cause a healthy battery's voltage to "drop like crazy." You also mention a 0.60 A reading in your latest post. A draw of 0.60 A would be 600 mA, not 60 mA. But even at that, a 600 mA draw, while definitely higher than should be expected, would not cause the voltage of a healthy car battery to "drop like crazy."

How confident are you that your battery is healthy? Also, with the seemingly intermittent nature of your no start issue, I'd suspect something like a bad battery cable connection. Somewhere along the line someone hasn't installed a temporary bolt-on battery connector end, have they? Those are not intended as a long-term solution and can easily allow corrosion to start forming at the connection and inside the cable insulation. Those are less common with the GM bolt through posts, but I have seen a few. Also, those GM bolt through posts can get corrosion between the bolt and the disc that contacts the battery inside and hidden by the insulation. Have you pulled the bolt out and made sure everything's clean inside as well?

-Rod

Hi Forums:

The vehicle shows a short going through these components/terminals:

INT BAT Fuse
RDO BAT Fuse 19
Instrument Panel Cluster Connector - Input thru A10/Output thru A6
Connector C203 - Thru L7

The current drain runs through connector C203 because the current drain stops while C203 is disconnected.

The schematic shows that Terminal L7 on connector C203 routes to Terminal G on Splice Pack SP201.
I therefore expected the short to route from L7 on C203 to Terminal G on SP201.

To verify this, I disconnected C203 and connected a wire from the male connector to the corresponding
female connector of each circuit through C203, one circuit at a time. Interestingly, I did not detect a short
along the wire from Terminal L7 on C203 to Terminal G on SP201.

However, three other circuits did show an increase in current through connector C203.
These circuits are: J6, J7, K6.

The info I have on these circuits is:
J6: Turn Signal Switch Output - Left Front - Circuit 1414
J7: Turn Signal Switch Output - Right Front - Circuit 1415
K6: Electronic Control Unit Ouput - 12 Volt - Inadvertant - Circuit 1732

It seems that these three circuits are not connected to the circuit that carries the short from the INT BAT
fuse to C203. If so, how does a short jump between unrelated circuits??

I hope that forum readers can offer troubleshooting ideas to move forward from this point.

Thanks in advance.

There are a lot of questions in prior posts that have been asked but not answered. Getting some answers to those questions might help us narrow your search and be able to ask better questions.

Where does C203 originate? Is it connected to the fuse/relay panel? A short circuit does exactly that, jump from one circuit to another circuit in a way not expected. That's why a short circuit will blow fuses. It would be helpful to understand how much current you're measuring between each of those circuits when using your jumper wires. Also, did you find the wiring diagram you're referencing online that you can provide a link to so we're all on the same page, or are you getting it from a book?

-Rod