LEEREED123
1/2 ton status
what are the effects of a bad ESC module?
would it effect fuel milage?
would it effect fuel milage?
CK5
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effects of an ESC module???
- Thread starter LEEREED123
- Start date
Bad ESC, I'm not sure the vehicle will even run.
LEEREED123 said:
I'm not sure, but it ranges from running like crap to not running at all. It can lead to reduced MPG and power.
The bypass procedure is very simple if you want to do it, and it's a GM-approved mod. It came out in a GM service bulletin.
y5mgisi
1 ton status
How do we do this bypass if you dont mind me asking?
y5mgisi said:
I'm looking for the "proper" way to do it. I had an engine fire and the harness that went from the distributor to the ESC was fried. I couldn't find a replacement, so I did the ESC bypass internally in the distributor.
The proper way calls for jumping two wires together on the interior side of the harness (behind the glovebox) and then unplugging the harness from the ESC module since it won't be used any more.
I'm just trying to remember which two wires.
.....
Ok, green and black. You should have a harness coming out of the back of the HEI going toward the glovebox area, near the heater box. On the other side of the firewall, behind the glovebox, jump the two wires together and unplug the harness from the ESC.
You'll probably need to retard your timing a bit. I don't remember to what, since it's been over a year and a half since I did this. But I'm pretty sure just setting it to match a pre-ESC HEI is called for. The ESC only retards timing, and does it via input from a knock sensor.
On my truck, I did it internally in the distributor and have no harness. I jumped pins 1 & 3 on the 3-pin side together using the original connector. I'm running out to take a pic now...
I *think* he is talking about TBI based on the vehicles in the profile. I just assumed that, if not, and it's standalone ESC, the above post is how you do it.
Pics as promised
First, here's where the ESC harness enters the firewall. It's missing on mine, and has a rubber line going to a vacuum gauge through the hole
Ok... on the right, the Ign. Module. On the end nearest the firewall, there's 3 pins. Connected to the pins is a passthrough connector. By "passthough" I mean it has a female end to connect to the module, and a male end which connects (originally) to the ESC harness. The passthrough is there because it also is what connects the module to the pickup coil, using either pins 1 & 2, or 2 & 3...can't remember which and didn't want to disassemble all the way. It's irrelevant if you're just bypassing the ESC.
I reused the ESC connector to make a jumper...pins 1 and 3 are connected, and the middle isn't used.
The 'notch' in the metal base of the distributor is where the ESC exits to head toward the firewall. I haven't blocked it off yet, but probably should, just to prevent water getting in there.
Here's a somewhat exploded view of the parts:
I left too much wire on my jumper harness, so I need to make sure it's tucked down nice and neat to avoid being caught up in the spinning rotor. If I redo it, the pins in the ESC connector are available at Pep Boys. I might do that with a much shorter wire for a cleaner installation.
Hope this helps!
First, here's where the ESC harness enters the firewall. It's missing on mine, and has a rubber line going to a vacuum gauge through the hole
Ok... on the right, the Ign. Module. On the end nearest the firewall, there's 3 pins. Connected to the pins is a passthrough connector. By "passthough" I mean it has a female end to connect to the module, and a male end which connects (originally) to the ESC harness. The passthrough is there because it also is what connects the module to the pickup coil, using either pins 1 & 2, or 2 & 3...can't remember which and didn't want to disassemble all the way. It's irrelevant if you're just bypassing the ESC.
I reused the ESC connector to make a jumper...pins 1 and 3 are connected, and the middle isn't used.
The 'notch' in the metal base of the distributor is where the ESC exits to head toward the firewall. I haven't blocked it off yet, but probably should, just to prevent water getting in there.
Here's a somewhat exploded view of the parts:
I left too much wire on my jumper harness, so I need to make sure it's tucked down nice and neat to avoid being caught up in the spinning rotor. If I redo it, the pins in the ESC connector are available at Pep Boys. I might do that with a much shorter wire for a cleaner installation.
Hope this helps!
dyeager535 said:
I thought the ESC was replaced with the ECM that came along with TBI...?
Because don't all TBI ignition modules have 7 pins instead of 5??
LEEREED123
1/2 ton status
MY APPOLOGIES! Yes, it is a TBI vehicle with an external esc module next to the master cylinder.
the reason i asked is that i have a fault code for an ESC but really no noticable problem. I was wondering about fuel milage, since mine has seemed to drop quite a bit.(6-8 mpg) so I was curious. had one in stock here at work, so I figure I'll put it in and see what happens.
the reason i asked is that i have a fault code for an ESC but really no noticable problem. I was wondering about fuel milage, since mine has seemed to drop quite a bit.(6-8 mpg) so I was curious. had one in stock here at work, so I figure I'll put it in and see what happens.
They are kinda pricey aren't they? I think I'd run down the ESC tests for that fault code before replacing it. Bad wire or connection anywhere in that circuit is a likely cause, as I recall the knock sensor feeds it and that wire/connector is pretty prone to failure.
broncoman6524
1/2 ton status
From my understadning...an esc hei dist has a 7pin module...the way i did it was unplugged the harness for the coil from the 7pin module removed the 7pin module from dist and unhooked it from the pickup coil. (green and yellow wire)
Then in my case i have MSD, so i used their magnetic p/u thingy that replaces all of this, if you have, or can get a 5or 4 pin module simply plug the coil harness and the pickup coil into it and you've bypassed the ESC.
I can get pics too if anybody wants them...ive got a spare dist and harnesses...
someone correct me if im wrong though...
Then in my case i have MSD, so i used their magnetic p/u thingy that replaces all of this, if you have, or can get a 5or 4 pin module simply plug the coil harness and the pickup coil into it and you've bypassed the ESC.
I can get pics too if anybody wants them...ive got a spare dist and harnesses...
someone correct me if im wrong though...
broncoman6524 said:
That's essentially what I did, but you must have pins 1 and 3 jumpered together as I did. They're essentially an "in" and "out". If not jumpered, the Ign. module will be sending data to a non-existent ESC, and excepting a response. By jumpering, you eliminate the ESC while completely the loop.
Here's your info on the circuit and how to troubleshoot it: http://www.thirdgen.org/techboard/tech-general-engine/240876-need-know-where-knock.html?highlight=maf+esc
Pretty basic, it's the knock sensor control.
Pretty basic, it's the knock sensor control.
broncoman6524
1/2 ton status
jonrpick said:
Correct, for retaining the stock 7pin esc module.
broncoman6524 said:
Actually, that was for the 5-pin... But this thread has me curious now. Is the ECM and ESC separate on the TBI motors?
broncoman6524
1/2 ton status
TBI doesnt have hei...so the distributeres will be different....I was speaking Hei...
broncoman6524 said:
LOL...then I'm confused. What mods would one be doing on the 7-pin model, and why would they be done?
But the question still stands... Does TBI have ESC, and is it separate from the ECM???
LEEREED123 said:
Uhh ... this module by the master ... does it, by chance, say "K-H" on it?
I'm thinking you have a 1990-91 truck, which has (lame) antilock brakes, which would be the module on the brake system.
Post up a pic... and also the code you're getting. Could be the antilock and they're crap ;D
-- A
broncoman6524
1/2 ton status
No, the tbi ESC is wired into the ECM. From my knowledge atleast.
Tbi dist.
Tbi with cap off, Note the difference in modules verses the HEI dist shown earlier by JonRpick.
wire from dist to coil?
Hei dist. 7pin ESC wiring (No module, or rotor shown)
4pin module (5pin looks same)
You will have to change the pickup coil as well if you have HEI and want to remove yuor ESC, this is because on the 7pin stuff the pickup coil wires go into a "T" as show in picture below. From what i know this isnt remove-able
Tbi dist.
Tbi with cap off, Note the difference in modules verses the HEI dist shown earlier by JonRpick.
wire from dist to coil?
Hei dist. 7pin ESC wiring (No module, or rotor shown)
4pin module (5pin looks same)
You will have to change the pickup coil as well if you have HEI and want to remove yuor ESC, this is because on the 7pin stuff the pickup coil wires go into a "T" as show in picture below. From what i know this isnt remove-able
Your pic with the missing module and rotor is a 5-pin HEI. Same one as in my pics. Look at the harness with the green, yellow and black wires.
It has 2 pins on the one side and 3 on the other, connected to the pass-through connector, then to the ESC harness.
The brown connector is the same one i used to make a jumper between pins 1 & 3 on that end of the module.
In fact, converting to a 4-pin module wouldn't be hard. It'd just require reconfiguring the wires on the pass-through connector to fit that particular module.
It has 2 pins on the one side and 3 on the other, connected to the pass-through connector, then to the ESC harness.
The brown connector is the same one i used to make a jumper between pins 1 & 3 on that end of the module.
In fact, converting to a 4-pin module wouldn't be hard. It'd just require reconfiguring the wires on the pass-through connector to fit that particular module.
