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92 S10 Wiring Gauges

30K views 26 replies 4 participants last post by  EOD Guy 
#1 ·
I have a few question so please hang in there. I am an avid forum researcher and from my lack of knowledge or understanding....., I am left with a bunch of unknowns.

Stock Info: 92 Chevy S10 Reg cab 2.5L engine with 700r4
Current state: Pulled out motor and trans, will be installing a 383 carbed (no choke) paired with a TH400 3000 stall NO lockup tranny.

Removed ECM and ECM wiring (Passenger side wiring), Will be a track truck primarily, A/C components removed, will run heat only.

I want to run everything from the wiring coming from the gauge cluster.

Gauges and accessories I am looking to run.
-Speedometer, Tach, fuel, volts, water temp, and oil pressure gauges
-Flexalite 480 fan and aeromotive A100 fuel pump.

Here is my wiring diagram.
.

I am a little confused on how to hook up my gauges. I have built a gauge cluster to house my (5) gauges, turn signal lights, and hi beam indicator. My quest is to wire all this without a hitch. :sweat: The numbers below correspond with the wiring diagram in the instrument cluster.

1. Gray - Instrument lamp fuse - There are 3-4 of these, one is in the oil pressure sending unit wires, another in a relay and the other two went into the ECM but are not connect now. All these wires are spliced together with the main one coming out of the ignition harness. I just want to know what it is or does and if I need it? My guess is its for dummy light activation if so then why are they all spliced together from one, how would the gauge cluster know which light to activate?

2.Pink/Blk - 12V ignition - I believe this will be connected to all 5 of my gauges (+) post? Also needs to go to alternator (3 wire).

3.Brown - Alternator - Volts gauge send wire

4.Tan/Blk - ECM Pin A2/Up shift light? Not sure if I need it or what its good for in my application?

5.Tan/Wht - Rear wheel anti lock (RWAL) & Ign Sw Pin G2? I removed the RWAL stuff but not sure if I need this wire or what it was for?

6.Dk Green - Water Temp sending unit, will go to gauge sender post

7.Dk Blue x2 - Dir/Haz lights, right turn signal - Right Turn signal light in dash

8.Pink - Fuel tank unit - Im guessing this powers the fuel pump

9.Tan-Oil pressure switch/sending unit - goes to oil pressure gauge post but also wondering why this wire has a orange and gray wire with it?

10. None

11.Brown/Wht - ECM Pin A5 (SES indicator) No idea what this is for or is?

12.Pink/Black - Same as #2, 12V ignition - Can I use this for my electric fan for power?

13.None

14.Lt. Blue/Blk -Speedometer/ Speed signal output - Dont think this will work since I removed ECM? Can it be used for anything else?

15.Yellow - Audio Alarm module - For fasten seatbelt light- wont be using this in new gauge panel setup

16. Lt. Green - Hi beam indicator light - Will go to blue light in my gauge panel

17. Black - Ground - Will be used to ground all my gauges

18. Lt. Blue x2 - Left turn signal and dir/haz light - will go to left turn signal light

If any of these are incorrect or you know the answer to my unknown please help a brother out. First time doing wiring and I dont have family who are into this kind of stuff to help out.

Lastly, I know tach I will run a wire from Coil to tach to get signal.
Speedometer I havent figured out but will wait on that till the end.
Other wires I have in my bay are this:
Orange (4-5) - 12V Constant
Red - Goes to Alternator
Purple - Starter
Thick Pink - Coil
Gray - Not sure what its for, same wire that is going into this relay below and spliced into the main gray wire coming from the instrument cluster I mentioned above. Believe it is a fuel pump relay? But why is oil pressure lines going into it also?


What I'm working with.... Please help!!!
Any questions please ask.

 
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#2 ·
You're probably not going to like my answer.......

It is possible to remove the ECM controlled fuel ejection and swap to a carb setup........ however it is almost impossible to remove the ECM and re-wire the system to use the stock ECM controlled signal components etc....... unless you know what you are doing and even then it's tricky......in your case the gauge cluster.

Might be easier to go with after market gauges and senders. Basically you need to pick a component ie.... the fuel pump.

The fuel pump at the tank needs two wires, 12v power and a ground, the pwr wires will run to the front of the truck to a relay - from the relay to a fused 12 volt source. The relay is connected to some sort of safety shut-off switch and controlled by a switched 12v source (Ignition switch). You need to figure which wire that is, Via your truck and wiring diagram, sometimes the wire controlling the relay is controlled by the ECM..... which you don't have anymore etc.....

The Fuel sender needs two wires, a ground and the fuel gauge sender feeder (normally Tan on GM). The actual fuel gauge needs three wires - A ground, a switched 12volt and the Tan wire from the fuel sender. If you want dash lights you'll need two additional wires - one from the headlight switch providing 12 volts and a ground etc....

All you dash lights grounds can be combined and all the 12 volt wires can be combined etc.......

As you can see it's not hard just very time consuming. You just have to pick a starting point, consult your diagrams, find the wires on the truck and figure out if the diagram says it went to the ECM .........you're going to have to go to older sensors to get it to work correctly etc.....

If you don't have a factory wiring diagram for the entire truck you are going to have a very rough time.....good luck.
 
#3 ·
I used all the factory gauges from my 2.5L '96 cluster on my '87 Buick GN swap. You just need to adapt over the S-10 sensors and run a capacitor on the tach leads to "recalibrate" it. Mine (4 cyl -> 6 cyl) ended up being a 0.0021mf (across C-103 slot from my records), but an 8 cyl will prolly be different. I tried a couple different caps on the cluster while running it against a known good tach throughout the RPM range and picked the one that was closest for all revs. Got that info from the "Jags That Run" web...

Russ
 
#4 ·
Thanks guys for the response!

EOD guy - that writeup is awesome and I appreciate the attention to my needs. I should of make this more clear but I am only running aftermarket gauges.

As this is my first undertaking, I'm no idiot but not having a background in this stuff it is a little intimidating but I'm more than capable of handeling it. I apologize first off but I didn't get the concept of how the wiring was put together and how I would convert to my gauges. Well after going through the schematicsas as you mentioned I finally found the answer to most of my post....I was just too wrapped up in the gauge wiring, but the pic below is all I needed to see....match it up to the corresponding gauge wire number and voila.....

The next quest will be to find the fuel relay information and if or where the relay is connected to a switch? My understanding is that the fuel pump and the oil pressure use the same relay and the fusable link would be the fuse block???

Concerning the tach, can I just run a wire from the (-) post on the coil and get a readout that way?
 

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#5 ·
Fuel pump relay easy day......

I installed a bypass switch on mine..... just in case the oil switch ever failed. My switch in under the hood, the banana plug is used to plug a jumper wire directly to the pos post on the battery.....if the fuel pump ever fails I can flip a toggle, plug in my jumper (I keep it in the trunk) and if it now works the oil switch failed etc.....

You do NOT need a bypass switch.
 

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#6 ·
I found this diagram and this is exactly how mine is/was connected. I have 4 wires coming from the relay. The green/wht went to the ECM, will this cause a problem not being hooked up or do I need a different relay with 3 wires instead of 4? What to do?

My fuel system is completely gone as of two weeks ago. So I will be running a fuel cell, which should be easy to hook up the sender to gauge. As for the pump, it gets its power through the relay? Would have never guessed.

Also the ECM B fuse I'm assuming routed through the ECM? Or is it through the fuse block? If through the ECM I will need some direction since my ecm is gone. Thanks ahead of time!
 

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#7 · (Edited)
The relay in your diagram is a single pole, single throw type.

In your diagram the fuel pump is receiving prom thru the oil press switch, thru a fuse (ECM B, which is in the fuse block not the ECM) from the ign switch....... AND thru the relay via Fuse B from the ign switch.

When you turn the key to start, both fuel pump circuits energize (relay and the oil press switch) ....... during the start cycle the engine hasn't built up oil pressure and the oil pressure switch is open and not providing juice to the pump, so the pump is getting juice from the relay because the ECM is energizing the relay allowing the pump to function etc.....

Once the engine starts and oil press switch closes, it also provides the pump with juice........ the ECM monitors the oil press switch and when it closes the ECM turns off the power to the relay and now the relay isn't providing juice.

The fuel pump is now getting juice only thru the oil press switch...... if the car is in accident and the engine dies and loses oil press the switch will open and the fuel pump shuts down...... safety measure. I used the same type safety concern in my version, only with no ECM. I used a 3 pole oil press switch and used the starter terminal (eliminates the ECM) to provide juice during startup
 
#10 ·
#14 ·
So I went ahead and bought a fuel pump relay at the local parts store. Now I'm a little confused on how to wire it. The verbiage is a little confusing to me. I have installed the ground to 85 terminal. Now I have the other three terminals left. The diagram shows a 12v fused going into the relay and also a hot in run coming from the ignition switch. I'm not sure which wires those are. The wires in my relay now... I have an orange wire the schematics call a 12v constant, a gray wire I'm not sure what its called but looks like it always runs back into illumination, and a green wire which I'm guessing was to the fuel pump. Which wires go where? How do i know if they are fused?
 
#16 ·
On a bosh type relay terminals 85 and 86 are interchangeable, they are the leads for the coil that energizes and closes the contacts in the relay.

Not understanding your questions...... are you talking about the wires on the new relay or from the wiring harness on the vehicle?
 
#26 ·
On a bosh type relay terminals 85 and 86 are interchangeable, they are the leads for the coil that energizes and closes the contacts in the relay.
EOD Guy has done an excellent job in helping you with your wiring problems. But there are relays out there that have a diode across the relay coil and those are polarity specific. I just finished wiring the headlights in my 76 Corvette using two of those style relays and terminal 85 is positive and 86 is negative.
 
#17 ·
I'm sure this is getting annoying... I'm like a lost dog here.

No, I'm talking about the wires coming from my vehicle which are still going to th e old relay. Orange is constant which I'm not sure if I can use that into 12v fused or as hot in run? The orange wire comes from ECM B 10A fuse whatever that means? Is that a 10 amp fuse?

Gray went to fuel pump prime and fuel tank unit.

Green went to fuel pump relay

Black is ground

This is what the original schematics are.
I'm confused why two wires from the relay both went to the fuel pump and where they are suppose to go now?

I'm just not sure which wires besides ground to hook up on the new relay. Should I be using a different wire not already in the old relay?
 
#18 · (Edited)
If you are talking about the existing wiring .....

Since you eliminated the ECM, you need to run a jumper wire from the existing Orn wire to the Grn/Wht wire that used to go to the ECM. You can tape off or remove the Gry wire that used to go to the ECM, if you decide to remove it, cut it at the splice.

If you are talking about wiring it like I did, I'll try to explain it better in another post
 

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#19 · (Edited)
Orange is constant which I'm not sure if I can use that into 12v fused or as hot in run? The orange wire comes from ECM B 10A fuse whatever that means? Is that a 10 amp fuse?

Answer: Use a multimeter and determine if it is hot all the time or only hot in run.

Gray went to fuel pump prime and fuel tank unit.

Answer: the diagram you posted doesn't show a prime (is that the fuel pump test connector)....... you need to determine if it's hot all the time or just in run or not hot at all until the relay is energized (which is what I believe it is, but you need to make sure)

Green went to fuel pump relay

Answer: Where does the other end of the green wire go? Old ECM, labeled as Grn/Wht on your diagram?

Black is ground
 
#21 ·
Only problem is no motor or trans to test wires, striped vehicle for new power plant. Wanted to get wiring done so I could "plug and play"....lol wiring obviously is not my strong point.... This and the heater are my last obsticals before test fitting motor and trans.
 
#22 ·
Perfect, I will wire it up just like that. Thanks brother! I've been looking for a while to find out if orange is hot in run only, where do you find your info....Google searches and schematics have me running in circles.

So i understand, on mine the Orange wire is hot in run and also fused.

Gray is not hot until engine is running. But I'll have to double check once I get motor running?

Thx again!
 
#23 ·
Get my info from my head and using the diagram you provided....lol

According to your diagram, I assume your orange wire is hot in run and fused. Once you get the battery back in and use a multimeter and verify that's what it is.

The gray wire will be hot in "run", may or may not be hot in "start".
The new wire from the starter will only be hot in "start"
The wire (grey?) that actually connects to the fuel pump will be hot in "run" and "start"
 
#24 ·
If you wanted..... using a 3 pole oil safety switch, it is possible to eliminate the relay in your application.

Using the old 2 pole oil safety switch you must use a relay.

The relay is used if you don't have a heavy enough gage wire from the ignition switch to carry the load of the fuel pump thru the ignition switch etc..... In my case that's what I had to do, In my original diagram I had a separate fused 12 supply wire because the wire wasn't heavy enough from my ign switch etc.... It appears from your diagram, the yours was wired from the factory with a heavey gage wire etc...
 
#25 ·
Thanks for the info, every time I go to close the door on this issue another one opens! Lol Do you think in my application it is necessary to have a relay? It looks like all the wires are the same gage. And there was already a relay and three prong in my old application? Just wondering, but as long as I keep the safety system that's all I care about! So if there is a better way I'm all ears!

I have a new wire I need help with, I'm assuming the wires all have the same value as before but just for shyts and giggles I traced back the wire from the fuel pump, there is a purple thin wire which is the sender wire for the gauge and a thick gray wire, when I follow this up, it goes into the firewall all by itself. So I'm assuming it's spliced behind the firewall into the other gray wires....at least this is what I gather from the schematics? But it is considerably thicker that the normal wires so it has to be for the fuel pump power.
 
#27 ·
Your guess is probably correct, but you have to check the gray wire for continuity all the way up to the existing relay and the oil press switch. If you don't KNOW where each and every existing wire starts and stops and what it's connected to...... very possible to short something out when you start re-wiring/modifying the existing system etc....... Once you let the smoke out of a wire it's impossible to get it back in.

Your choice on the relay, as you are having a little difficulty understand the existing system, I'd modify/replace the existing relay and oil press switch..... once that works correctly you can play around with eliminating the existing relay etc.....
 
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