VATS bypass

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Aug 3, 2025 | 02:33 PM

#21

Tunedport90

Melting Slicks

Joined: Aug 2011

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https://www.gearhead-efi.com/Fuel-In...mation-DA2-DA3

The pinout and schematic for the 92-93 lt1 ecm. If sea is on the ecm is powered up. The ecm should do a 2sec control of fp relay. Sounds as if you ecm still isn’t working properly. Iirc it’s a firmware default to do the prime not related to the chips settings. Concerning the fan kicks on Koeo.

Aug 3, 2025 | 05:40 PM

#22

IHBD

Melting Slicks

Joined: Nov 2016

Posts: 2,256

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From: So Cal

2023 C4 of the Year Finalist - Unmodified

There are 4 different "starter relay" circuits and strategy in the 13 model years of "C4". 84-85, 86-89, 90-92, and 93-96.

All 4 are in this thread now. The nuances of the particular year isn't being addressed or discussed. Without disclosing the actual year, and the respondent being familiar with that particular year's set-up, y'all are going be frustrated.

Last edited by IHBD; Aug 3, 2025 at 07:44 PM.

Aug 4, 2025 | 12:32 PM

#23

canucklehead2004

Intermediate

Joined: Apr 2025

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Mine is 89 and I did the jumper wire bypass for the relay. I was able to pop the plastic top cap off my old relay so i shoved the bypass connector into that plastic cap so i could screw it back onto the middle divider and slide it back in place. It seemed there wasn't a lot of tension on the bypass wire spade connectors into factory harness so I am concerned they could rattle loose over time. Hoping this might keep it a bit more secure and from moving around too much. i will keep a Philips screwdriver and 7mm socket handy if i need to dig into it again. Car started fine, no issue. i need to take long drive to see if it fixed the hot no-start issue i was having.

My replacement relay from Ebay arrives this week. i ordered it before i saw Tunedport90s fix. I don't plan to install it.

Apr 28, 2026 | 08:05 PM

#24

canucklehead2004

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Joined: Apr 2025

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Friday we went for 1.5 hour drive and no issue, same when we came home driving another 1.5 hours. Today I drove 15 mins , spent 10-15 mins with glass guy then it wouldnt start.

When I bypassed the "starter enable relay" behind console, does this completely bypass the VATS...as in chipped key is bypassed and it should work like regular ignition that I just turn to start?

I also tried shifting into N to start, no luck. It is not making any sounds at all, I don't hear click and obviously no crank.

Apr 29, 2026 | 11:24 AM

#25

canucklehead2004

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Joined: Apr 2025

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I went back to car about 2 hours later and it fired right up using original old key.

Jun 15, 2026 | 12:51 AM

#26

macroblock

4th Gear

Joined: Jan 2026

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In the 1990 model year, the VATS lockout time is approximately 3 minutes for the first 3 tries, then approximately 10 minutes after that. It is also 10 minutes if you disconnect and reconnect the battery during a lockout.

The 1991 thru 1996 model years only use the approximate 3-minute VATS lockout.

The VATS lockout is actually a loop counter and not a real time counter, so the VATS lockout time is not exact. For example, 7200 CCM program execution loops normally takes just over 2:30 minutes.

Last edited by macroblock; Jun 15, 2026 at 12:53 AM.

Jun 15, 2026 | 12:23 PM

#27

canucklehead2004

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Joined: Apr 2025

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For 1989 model: if you have bypassed VATS key with the resistor mod and also jumped the starter enable relay as per post 15 from Tunedport90, does the VATS lockout timer even come into play?