7747 Check engine light on but no codes

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05-30-2023
NorCal69

7747 Check engine light on but no codes

I just finished up my third TBI swap.
I purchased a very lightly used Howell kit for an AMC 304 V8 and installed it on a Buick 231 V6. Long story, but the previous owner could not get his engine to run properly, pulled the kit off and went back to a carb setup.
The injectors were swapped to 4.3 size and the an appropriate prom chip installed for the engine. The engine runs excellent but the check engine light stays on constantly.
If I jumper the ALDL plug to flash for codes the light does not flash, it just stays lit the entire time.
When hooked to my Snap On "brick" scanner the computer is not throwing any codes.
Any ideas as to what would cause the check engine light to stay on constantly?
Asking Howell is a waste of time as I am not the original purchaser of the kit.
Attached is a video of the engine running.

https://i.imgur.com/sUi2yRM.jpg
https://vimeo.com/831089969?share=copy
05-31-2023
Six_Shooter

7747 ECM? If so did you also swap the CALPAK for a V6 CALPAK? If you didn't you are likely seeing a cyl count mismatch. Soft codes won't be stored if you turn the key off, so you need to stall the engine if you want to pull a code set while running. Disconnecting power from the coil will stall the engine. However a cyl count mismatch should come up without the engine running.
05-31-2023
NorCal69

Quote:

Originally Posted by Six_Shooter

7747 ECM? If so did you also swap the CALPAK for a V6 CALPAK? If you didn't you are likely seeing a cyl count mismatch. Soft codes won't be stored if you turn the key off, so you need to stall the engine if you want to pull a code set while running. Disconnecting power from the coil will stall the engine. However a cyl count mismatch should come up without the engine running.

I will pick up a V6 CALPAK and give that a try.
I was told by the person who burned my prom chip that the CALPAK did not matter if it was from a V6 or V8.
I have a 1228062 ECM on hand, any chance that the V6 CALPAK from an ECM 1228062 would work in my 1227747 ECM?
05-31-2023
1project2many

[quot]The engine runs excellent but the check engine light stays on constantly.
If I jumper the ALDL plug to flash for codes the light does not flash, it just stays lit the entire time. [/quote]

This is a problem. You should see code 12 with the key on, engine off, and ALDL jumpered. Doesn't matter what other codes are present.

Start with the "ecm self test" function. Turn the key off for five minutes. Then turn the key on but do not start the vehicle. The check engine light should light for a few seconds, turn off for a few seconds, then light and remain lit. If this function is not happening you need to: 1) confirm the wiring for the check engine lamp is correct, and 2) confirm the prom is not corrupt or installed incorrectly. Confirming the prom is a matter of removing it and installing a known good prom, then going through the steps
for the self test again.
06-01-2023
NorCal69

Quote:

Originally Posted by 1project2many

[quot]The engine runs excellent but the check engine light stays on constantly.
If I jumper the ALDL plug to flash for codes the light does not flash, it just stays lit the entire time.

This is a problem. You should see code 12 with the key on, engine off, and ALDL jumpered. Doesn't matter what other codes are present.

Start with the "ecm self test" function. Turn the key off for five minutes. Then turn the key on but do not start the vehicle. The check engine light should light for a few seconds, turn off for a few seconds, then light and remain lit. If this function is not happening you need to: 1) confirm the wiring for the check engine lamp is correct, and 2) confirm the prom is not corrupt or installed incorrectly. Confirming the prom is a matter of removing it and installing a known good prom, then going through the steps
for the self test again.[/QUOTE]

The light will not flash at all. From the time I turn the key on the light just stays on.
The wiring to the light is just a power and a ground. The bulb socket has a single power wire coming off of it. The bulb socket grounds itself to the speedometer housing. I ran the power to the light bulb wire and the ground to the speedometer housing.

I ordered a v6 CALPAK chip today.
I have another prom chip that I can test with as well.

The jeep does run well and the data on my scanner looks great too.
06-01-2023
Six_Shooter

Quote:

Quote:

Originally Posted by NorCal69

This is a problem. You should see code 12 with the key on, engine off, and ALDL jumpered. Doesn't matter what other codes are present.

Start with the "ecm self test" function. Turn the key off for five minutes. Then turn the key on but do not start the vehicle. The check engine light should light for a few seconds, turn off for a few seconds, then light and remain lit. If this function is not happening you need to: 1) confirm the wiring for the check engine lamp is correct, and 2) confirm the prom is not corrupt or installed incorrectly. Confirming the prom is a matter of removing it and installing a known good prom, then going through the steps
for the self test again.

The light will not flash at all. From the time I turn the key on the light just stays on.
The wiring to the light is just a power and a ground. The bulb socket has a single power wire coming off of it. The bulb socket grounds itself to the speedometer housing. I ran the power to the light bulb wire and the ground to the speedometer housing.

I ordered a v6 CALPAK chip today.
I have another prom chip that I can test with as well.

The jeep does run well and the data on my scanner looks great too.

What you describe is just a light, not a CEL (Check Engine Light). The CEL gets 12V ignition power and a wire from the ECM that grounds the light to turn it on. I don't recall the pin number off hand, but it is a brown/white wire.
06-01-2023
NorCal69

Quote:

Originally Posted by Six_Shooter

What you describe is just a light, not a CEL (Check Engine Light). The CEL gets 12V ignition power and a wire from the ECM that grounds the light to turn it on. I don't recall the pin number off hand, but it is a brown/white wire.

I am working with an Howell harness that I purchased used. The original purchaser was never able to get his vehicle to run properly and removed the kit without ever leaving the garage.
The harness provides two leads to the CEL. One is a power supply and the other is a ground. I wired the CEL exactly the same way that I have in previous installations. This has me thinking that there is something wrong with the ECM or mismatch of PROM calibration and CALPAK cylinder counts.

https://i.imgur.com/Adr2ZtA.jpg
06-01-2023
tayto

what # on the connector does the SES ground wire goto? should be A5...
06-02-2023
NorCal69

Yesterday I was looking over a previous TBI install and something donned on me.
Initially when I wired this kit I had a single lead bulb housing and connected the ground to the speedometer housing. I realized that that CEL light housing needed to be isolated with a ground wire and plastic housing. A little digging through the jeep parts stash produced this housing. Sure enough, the CEL light functions as it should now.

https://i.imgur.com/Vtpu4Ok.jpg