5.3 4L60E swap PRND idle question

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Working on a '58 Impala with a 5.3/4L60E swap. Using an HPI harness, no provision for the factory 4L60E neutral switch on the transmission (driver side plug). ECU is P01 01 Silverado. It appears none of the aftermarket harnesses provide a plug for the 4L60E NSS.

My issue is the ECU in key on engine off thinks it's in 3rd gear, and upon starting the engine thinks it's in 1st gear. It will always utilize the park/neutral IAC settings and never use the drive settings. My choice for idle at the moment is to dial it in for drive and high idle when in PN, or dial it in for PN and idle very low in drive potentially causing some stalling issues.

Engine is modified FWIW. Truck Norris cam, Sheet metal intake. Clearly needs different idle airflow targets for park versus drive. What is everyone doing when they use a swap harness to tell the ECU when it is in park/neutral versus drive? Just wire up a NSS to the ECU and not worry about the connection on the trans? Does the trans connector tell it when you select 3 vs D?

[leonpiper69]

You got me thinking, I was coking on here to ask a question and you might have helped point me in a direction.

I will tell you what your question makes me think of then post my own.

I just installed a painless harness on my LS1 with a 4l60e in my chevelle and while making connections I came across a two wire connection that the harness directions said it needs to run correctly....."gear indicator switch" is what it is called.

Painless says it needs to be connected to run right....I was thinking (and told by others) it just lights up the dash to tell what gear you are in. But if it tells the ECU what gear you are in, that could be your problem as well as mine.

[bk2life]

Working on?

i dont have aprndl swithc on my truck. I have it look for what gear internally. There is a selection for that in the transission tab.
been like that for 5 years

[Alvin]

Working on a '58 Impala with a 5.3/4L60E swap. Using an HPI harness, no provision for the factory 4L60E neutral switch on the transmission (driver side plug). ECU is P01 01 Silverado. It appears none of the aftermarket harnesses provide a plug for the 4L60E NSS.

My issue is the ECU in key on engine off thinks it's in 3rd gear, and upon starting the engine thinks it's in 1st gear. It will always utilize the park/neutral IAC settings and never use the drive settings. My choice for idle at the moment is to dial it in for drive and high idle when in PN, or dial it in for PN and idle very low in drive potentially causing some stalling issues.

Engine is modified FWIW. Truck Norris cam, Sheet metal intake. Clearly needs different idle airflow targets for park versus drive. What is everyone doing when they use a swap harness to tell the ECU when it is in park/neutral versus drive? Just wire up a NSS to the ECU and not worry about the connection on the trans? Does the trans connector tell it when you select 3 vs D?

Sounds like you are looking at "Trans current Gear" for this.. That is normal behavior. This is not the pid you want to look at for this.

There is a separate pid "PRNDL status" or something along those lines. That will show if it reading park or gear.

Even though you don't have a spot on the side of your trans.. There is nothing keeping you from putting a switch on the shifter. Most aftermarket shifters have provisions for this.

[Life is an Enigma]

Go to time 16:55 in video.

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Thanks for the replies!