What are these relays on my firewall and do I need them?

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louu

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All the emissions stuff on this truck is gone. I'm in the process of putting on an aftermarket fuel injection system on. All I need from the stock harness is power to the port on the HEI distributor. Are these two black boxes necessary?

The harness on this truck is a mess and I'm hoping to clean it up. Looks like so many people have chopped it up over the years
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45acp

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14087500 is a air injection control module and 14094774 is a electronic brake control module. If you Google these part #'s you may be able to get a little more information than I can give you. Good luck!
 

Scott91370

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What year is this on? I couldn't imagine anything newer than the 87 having air injection on it - but I did have an 89 Isuzu with it so it's possible.
 

fender89

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do we know if its possible to get rid of the air injection module? im looking for a replacement online but cant seem to find one. not abig deal if i can delete it.. anyone know?
 

AuroraGirl

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What year is this on? I couldn't imagine anything newer than the 87 having air injection on it - but I did have an 89 Isuzu with it so it's possible.
Air Injection was on a lot of 2000s gm vehicles, it has to do with converter choice and how the factory manifolds end up flowing as well as emissions. Like my 99 park avenue does NOT have 2nd-ary air but if it was a California emisisons, it would have that system added on with a electric air pump and a different exhaust crossover and a check valve etc.

do we know if its possible to get rid of the air injection module? im looking for a replacement online but cant seem to find one. not abig deal if i can delete it.. anyone know?
Does your truck have cats on it? Do you have emissions testings? Do you have an 87 with TBI? If you dont have cats, testing, and do not have fuel injection(electronic carb maybe?) you shouldnt need the system. but you would help a lot if you took a pic of your engine bay from a slight distance so we can see your manifolds, engine accessories, and whats on the engine
 

AuroraGirl

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All the emissions stuff on this truck is gone. I'm in the process of putting on an aftermarket fuel injection system on. All I need from the stock harness is power to the port on the HEI distributor. Are these two black boxes necessary?

The harness on this truck is a mess and I'm hoping to clean it up. Looks like so many people have chopped it up over the years
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can you take a pic of the engines front acessories and a shot including the manifolds on there currently? Also, you have a SPID label by chance? Pic of that?
did this truck have a VECI label on the air cleaner/core support/hood/underhood somewhere with a emissions statement/systems used/certification for use in __ that you could show too
 

fender89

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Air Injection was on a lot of 2000s gm vehicles, it has to do with converter choice and how the factory manifolds end up flowing as well as emissions. Like my 99 park avenue does NOT have 2nd-ary air but if it was a California emisisons, it would have that system added on with a electric air pump and a different exhaust crossover and a check valve etc.


Does your truck have cats on it? Do you have emissions testings? Do you have an 87 with TBI? If you dont have cats, testing, and do not have fuel injection(electronic carb maybe?) you shouldnt need the system. but you would help a lot if you took a pic of your engine bay from a slight distance so we can see your manifolds, engine accessories, and whats on the engine

I am not the OP here. I just have a similar question and i found this thread instead of making a new one. anyhow my truck is a 1985 k20. no cats. no emissions testing where i live. it has a holly 600 carb on it with vortec head. here are a few pics under the hood. I am in the process of replacing the ignition parts and cleaning up the engine. also i recently bought the truck and not totally sure exactly what was done to it.
 

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AuroraGirl

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I am not the OP here. I just have a similar question and i found this thread instead of making a new one. anyhow my truck is a 1985 k20. no cats. no emissions testing where i live. it has a holly 600 carb on it with vortec head. here are a few pics under the hood. I am in the process of replacing the ignition parts and cleaning up the engine. also i recently bought the truck and not totally sure exactly what was done to it.
I wouldnt touch it if it isnt bothering you, but if you are bothered, I would unhook it, tie the plug into the harness and wrap it with a harness tape. and then sell the module. It certainly isnt doing anything(did you google the number to know what it does) because you have carb and headers and i dont see a smog pump(which couldnt pump into anything anyway)
 

fender89

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I wouldnt touch it if it isnt bothering you, but if you are bothered, I would unhook it, tie the plug into the harness and wrap it with a harness tape. and then sell the module. It certainly isnt doing anything(did you google the number to know what it does) because you have carb and headers and i dont see a smog pump(which couldnt pump into anything anyway)
no thats fine its not bothering me. i was just confused as to why its there. I wanted to have a backup just incase it failed. but since its not doing anything I will just leave it. Thank you for the response.
 

AuroraGirl

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I am not the OP here. I just have a similar question and i found this thread instead of making a new one. anyhow my truck is a 1985 k20. no cats. no emissions testing where i live. it has a holly 600 carb on it with vortec head. here are a few pics under the hood. I am in the process of replacing the ignition parts and cleaning up the engine. also i recently bought the truck and not totally sure exactly what was done to it.
But if you want some pro tips, is your Booster vacuum line rated for brake booster? thats a long section of rubber line if the walls arent strong they could collapse under heavy vacuum and this would cause weird behavior on your brakes probably. If needed, Use a short section of tubing between the carb and the carbon fume filter to shorten the amount of hose used.
Also, I see a PCV with no breather or thing in the opposite corner of the driver side valve cover to complete the system? Is your passenger valve cover have 2 openings on it? Basically if your PCV valve is there you would need a tube and grommet to your air cleaner or a push in filter for that corner to allow air to pull into the crankcase. diagnolly is the name of the pcv game.

also your heater hoses, are they proper heater hose? they look almost like they maybe arent, but if they are thats ok. I would toss a new 15 psi cap on your system, that looks old. Also, your overflow hose is confusing me a bit, it doesnt look like a coolant hose either especialy a low pressure overflow tube. if you can, putting your overflow on the pass side would be way shorter to run and you can probably find a factory type reservoir that would screw into your core support over there. Just an idea.

Electrical, your setup is concerning.
You always want the ground post to be closest to the core support/fender and the positive to be closer to the engine, if it shifted or something fell, it wouldnt be shorting to power only adding a temporary ground connection. New cables may be wise. Engine block to neg, engine to firewall(both heads is best), frame to battery neg, and fender to battery neg are a good group of things to do for your grounding. The cable from the alt bracket to the battery is a common one for sure, just ensure the bracket itself is cleanly connected to the engine and the alternator is well connected to the bracket. Then bracket cleanly to battery. Otherwise adding more engine-to-bracket grounds could help but you have a low amount of electronics, youre good probably.

Hose clamps. Screw clamps should be avoided, Tbar, Fuel injection, constant tension(mubea) and similar clamps are superior but if you have no leaks you can cheat it for a while. Just know that screw clamps will usually bite in over time and then weep because the hose isnt held as strongly.
You also are possibly missing a rubber seal on your cowl/firewall/hood interface, but i dont have an 81+ so I may be wrong on that, but it looks strange

Also your brake master cylinder is seemingly from an older truck, does this truck have big or small rear drums and whats the gvw do you know?


Also, can you send a pic of your distributor weights, I see you have that apart.
 

AuroraGirl

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NOTE: 1985-1990 models equipped with the LE8 (454) and H5D have an override relay. (See Figure A7-17-3) . This
relay is necessary dur to the lower cranking speed of the LE8 (454) engine. If the relay fails, the CEL will
come on. If it becomes necessary to replace the relay or the module, use the part numbers listed in
Figure A7-17-4.
Figure A7-17-4 - 454 and H5D Override Relay Parts List
7-103
GM PART NO. DESCRIPTION & APPLICATIONS QUALITY
100669221 Module 1985-89 W/LE8 454 1
14087500 Module 1985 W/LT9 350 1
14102010 Module 1986 W/LT9 350 1
14100876 Module 1985-Current W/L25 292 1
15528707 Relay 1985-89 W/LE8 454 1
14103304 Relay 1990-1993 N/L19 454 1
10052973 Module 1990-1993 N/L19 454 1
10052954 Module 1994 N/L19 454 1
APPENDIX 7.17
H51) EMISSION SYSTEM
(Cont'd)
10052954 (4815A)
11501907 (4815K)


It appears to be for controlling rudimentary emissions on your vehicle, the part number specifically is to a 1985 LT9 SBC which is an "HD" emissions RPO for a 350 which in my 1980 year was low components, could use leaded gas, and also was "high torque" but in 85 I am not sure. You should be fine. does your truck have a Check engine light? And does your gas gauge say unleaded fuel only?
 

fender89

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But if you want some pro tips, is your Booster vacuum line rated for brake booster? thats a long section of rubber line if the walls arent strong they could collapse under heavy vacuum and this would cause weird behavior on your brakes probably. If needed, Use a short section of tubing between the carb and the carbon fume filter to shorten the amount of hose used.
Also, I see a PCV with no breather or thing in the opposite corner of the driver side valve cover to complete the system? Is your passenger valve cover have 2 openings on it? Basically if your PCV valve is there you would need a tube and grommet to your air cleaner or a push in filter for that corner to allow air to pull into the crankcase. diagnolly is the name of the pcv game.

also your heater hoses, are they proper heater hose? they look almost like they maybe arent, but if they are thats ok. I would toss a new 15 psi cap on your system, that looks old. Also, your overflow hose is confusing me a bit, it doesnt look like a coolant hose either especialy a low pressure overflow tube. if you can, putting your overflow on the pass side would be way shorter to run and you can probably find a factory type reservoir that would screw into your core support over there. Just an idea.

Electrical, your setup is concerning.
You always want the ground post to be closest to the core support/fender and the positive to be closer to the engine, if it shifted or something fell, it wouldnt be shorting to power only adding a temporary ground connection. New cables may be wise. Engine block to neg, engine to firewall(both heads is best), frame to battery neg, and fender to battery neg are a good group of things to do for your grounding. The cable from the alt bracket to the battery is a common one for sure, just ensure the bracket itself is cleanly connected to the engine and the alternator is well connected to the bracket. Then bracket cleanly to battery. Otherwise adding more engine-to-bracket grounds could help but you have a low amount of electronics, youre good probably.

Hose clamps. Screw clamps should be avoided, Tbar, Fuel injection, constant tension(mubea) and similar clamps are superior but if you have no leaks you can cheat it for a while. Just know that screw clamps will usually bite in over time and then weep because the hose isnt held as strongly.
You also are possibly missing a rubber seal on your cowl/firewall/hood interface, but i dont have an 81+ so I may be wrong on that, but it looks strange

Also your brake master cylinder is seemingly from an older truck, does this truck have big or small rear drums and whats the gvw do you know?


Also, can you send a pic of your distributor weights, I see you have that apart.
i appreciate all the advice. I will definitely take you up on that. Will shorten the break booster vac lines great idea.
The pvc valve leads to the aircleaner. i just currently have it removed.
The heater hoses are infact heater hoses i just picked them up from autozone.
Great idea for the overflow i will look into that.
I will go over my electrical again and make sure it is properly setup.
I will get some new clamps. some that you listed .
The truck does not specify un-leaded fuel only.
The truck also has a check engine spot on the instrument panel but i am unsure if there is a light behind it or not.
recently took off the AC unit. will be buying proper caps for the AC lines.

The GVWR is 8600. not seeing the GVW anywhere. The drums do seem large.
 

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AuroraGirl

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i appreciate all the advice. I will definitely take you up on that. Will shorten the break booster vac lines great idea.
The pvc valve leads to the aircleaner. i just currently have it removed.
The heater hoses are infact heater hoses i just picked them up from autozone.
Great idea for the overflow i will look into that.
I will go over my electrical again and make sure it is properly setup.
I will get some new clamps. some that you listed .
The truck does not special un-leaded fuel only.
The truck also has a check engine spot on the instrument panel but i am unsure if there is a light behind it or not.
recently took off the AC unit. will be buying proper caps for the AC lines.

The GVWR is 8600. not seeing the GVW anywhere. The drums do seem large.
All right. So your truck doesn’t say unleaded only? Does the check engine thing light up at key on? If not, you have nothing you need to do, I would take and sell that module in my opinion

Pcv goes to the air cleaner?! Your carburetor has a port for PCV, it should connect to the valve. The opposite corner(other valve cover, in the back) needs to have a grommet with either a tube that connects to air cleaner or has a push in air filter (breather)
 

fender89

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All right. So your truck doesn’t say unleaded only? Does the check engine thing light up at key on? If not, you have nothing you need to do, I would take and sell that module in my opinion

Pcv goes to the air cleaner?! Your carburetor has a port for PCV, it should connect to the valve. The opposite corner(other valve cover, in the back) needs to have a grommet with either a tube that connects to air cleaner or has a push in air filter (breather)
whops i entered that incorrectly pcv valve does go to the carb. the driver side valve cover has a hole in it that with hose that runs to the air cleaner.

no the check engine light does not turn on when starting the truck .
 

AuroraGirl

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whops i entered that incorrectly pcv valve does go to the carb. the driver side valve cover has a hole in it that with hose that runs to the air cleaner.

no the check engine light does not turn on when starting the truck .
Key on specifically, not starting. But if not, thats good. Also, i may not be 100% correct on this, but your drums are bigger, is your truck have C6p on the SPID label at all, the bigger rear brakes, in my mind, would see you have the next size up master cylinder(plus yours would have a plastic reservoir in 85 i think?) but i could be wrong. it matches my 78 k10s master/booster, but my 80 gmc has the master with 2 hold down wires and I also have larger rear brakes but htat is because I have c6p.
 

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