1994 Lexus LS400 4806V remote start troubles

Hey guys, I have a 1994 model LS that I've been trying to install this Viper 4806V keyless entry and remote start system on for the past 5 days! I've gotten everything figured out and wired up except for the remote start wires. I've followed another forum on a guy who installed a security system on his 1990 LS and he seemed to have no problems with the remote start. The car will only remote start correctly if the key is in the ignition and turned the to the ON position. It will not start correctly in any other position. If I attempt to start the car with the ignition in the OFF or accessory position the car will only attempt to start and crank three times accepting failure. I even disconnected the accessory, ignition 1, and ignition 2 wires on the remote starter side and the car was still able to start when the key was in the ON position. I did not think this car used a chip sensing ignition that only allows it to only start with the key but I may be wrong! I can't seem to figure it out so I'm asking for help from the forum before I wave the white flag and take it to Best Buy and have them figure it out for an outrageous $200.

[UPDATE] I hooked the acc, ignition 1, and ignition 2 wires to the corresponding wires on the vehicle from the remote start and the vehicle starts but the remote starter continues to spin the starter indefinitely.

Did you hook up and learn tach ?

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If i Can't Install it    I Don't need it   Joe

Could you list your wire connections from the Viper to what wire on the car. Color and location.

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Definitely tach OR incorrect IGN wire, a 94 Lex was too early for an OEM immobiliser.
List your connections, 2 ignitions and possibly 2 starter wires.


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Amateurs assume, don't test and have problems; pros test first. I am not a free install service.
Read the installation manual, do a search here or online for your vehicle wiring before posting.

Alright here are all the wires and the connections.

MAIN HARNESS:
H/1:Red 12VDC Constant Input - WHITE/ Blue Constant
H/2:Black Chassis Ground - Ground to Chassis
H/3:Brown (-)200mA Horn Honk Output - GREEN/ Red Horn Wire
H/4:WHITE/ Brown Light Flash Iso wire - N/A
H/5:White Pin 30 of Light Flash Relay - Green w/Silver Park Lights
H/6:Orange Grd when armed output - N/A
REMOTE START HARNESS:
1:RED / Black 12VDC Constant Input - WHITE/ Blue Constant
2:Pink/Black Flex Relay Input - N/A
3:Pink/White Ign 2 - BLACK / YELLOW Ign 2
4:Red 12VDC Constant Input for Ign 1 Relay - WHITE/ Blue Constant
5:Violet Starter Output - Red w/Silver Starter Wire
6:Orange ACC Output - Pink/Blue ACC Wire
7:RED / White 12VDC Constant Input for Ign 2 - WHITE/ Blue Constant
8:Pink Ign 1 Input/Output - BLACK/ Orange Ign 1
AUX/SHUTDOWN HARNESS:
3:RED / White (-)200ma Trunk Release Output - Blue Trunk Switch Wire
4:BLACK / YELLOW (-)Dome Light Output - RED / White Door Trigger Wire
12:Violet/White Tachometer Wire - Black Wire @ Instrument Cluster
13:BLACK/ White (-)Neutral Safety - Chassis Ground
20:Brown Brake Shutdown Input - GREEN / WHITE Brake Switch Wire
DOOR LOCK:
1:Blue 500mA (-)Unlock Output - Green,GREEN/ Black wire @ Blue Connector
2: Empty
3:Green 500mA (-)Lock Output - GREEN/ YELLOW Wire @ Blue Connector


I did not post all the wires but I did post all the wires that I connected.

Yes, I did learn the tach signal. The antenna led glowed solid blue to show that it was successfully learned.

This is the tutorial I followed. 1990 Ls400 Remote Start/Alarm Installation!!

ls400club wrote:

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This is the tutorial I followed. 1990 Ls400 Remote Start/Alarm Installation!!

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This was incorrect. It's actually this link. 1990 Ls400 Remote Start/Alarm Installation!

I would try a different source for the TACH signal.

https://www.commandocaralarms.com/wiring/1990-1994/lexus/ls400/1294.html

https://www.bulldogsecurity.com/bdnew/vehiclewiringdiagrams.aspx

Your wire connections at the ignition switch look to be correct, Did you verify the function of those wires with a DMM?
Are your connections soldered or just T-Taps?
Didn't see a hood pin shutdown on your list. Very Important safety feature.


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I actually have the wires spliced together and taped up the old fashion way. I didn't install the hood pin switch because I didn't think it was that necessary.

What I don't understand is that it remote starts perfectly fine with the ignition in the on position. I'd think that the tach wire is working if it starts in the on position.

It means one of your ignition wires is incorrect.

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Amateurs assume, don't test and have problems; pros test first. I am not a free install service.
Read the installation manual, do a search here or online for your vehicle wiring before posting.

I've literally studied the wiring diagrams for that car and I have every ignition wire connected to the correct ignition wire on the viper module.

Test your wires for their function.
Try a different source for the TACH.
Possible the Pink/White is not set for Ignition 2.
As Howie started above.

Wiring diagrams are a GUIDE. Wires in car might be different than listed. Colors fade, Might be two of the same color scheme in same harness... Use your DMM to test and verify. Also check the Pink/White with a DMM to make sure it is set to Ignition. Not Starter or Accessory.


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In fact from what I remember, Toyotas use BOTH wires as ignition one, i.e. BOTH are required to start.

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Amateurs assume, don't test and have problems; pros test first. I am not a free install service.
Read the installation manual, do a search here or online for your vehicle wiring before posting.

Okay I'll look into it some more. Here's a video of what it's doing.remote start troubles

Verify the function of both ignition wires as you start the car with the key. Both wires should maintain voltage during cranking.

Now test them while you try to remote start. Do this without the key in the ignition.

If one of the two wires has power initially, but it drops to zero during cranking, it is programmed as an accessory wire, not an ignition wire. Reprogram to ignition.

If one of the wires has no output at all, double check the fuses/connections in the heavy gauge remote start harness.

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My ex once told me I have a perfect face for radio.

I just checked the wires with the key and a multimeter. The ignition 1 wire drops power during cranking. The ignition 2 wire maintains voltage. The acc wire also drops current during crank. On the remote start module the ignition 1 and ignition 2 wires stay constant during crank. The acc wire from the module drops current though.

The starter from the module that I have connected to the car's starter wire is actually showing open line during cranking with the remote start button. However, the only ignition wire from the module I have connected is the ignition 2 wire.

Watched the video.

Get rid of the blue quick clamps.
Did you change the source for the tach?

Maybe turn the engine sensing to voltage or turn it off for the moment until you get the remote start function figured out.

Those quick connectors are a headache to start with and will continue to be one.


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I still have the tach wire connected to the black wire behind the instrument cluster. I'm beginning to think that I be no choice but to run the wire to the engine bay and connect it to the black wire at the igniter. I'd hate to go through all that trouble and still have the remote start not work... I do have the systems engine checking set to tachometer. I'll try changing it to off or voltage sense.

That blue ttap is actually the only one I have left in the car because I removed all the others that didn't work well lmao. It's connecting the starter wire from the module to the car's starter wire.

The vehicle starts, but the starter keeps running.

1. Is the system programmed for engine checking off or virtual tach voltage sense? When programmed
for either of these features, the engine cranks for the pre programmed crank time regardless of how
long it takes for the vehicle to actually start. Adjust to a lower cranking time.
2. Was the Tach Learn successful? The LED must light solid and bright to indicate a successful learn.
3. Make sure that there is a tach signal at the PURPLE / white tach input wire of the remote start. If there
is not a tach signal, recheck the connection to the vehicle’s tach wire and make sure the wire is not
broken or shorted to ground leading to the remote start.
4. Is an ignition or accessory output wire connected to the starter wire of the vehicle? Verify the color
of the starter wire in the vehicle and confirm that an ignition or an accessory output is not connected
to that wire

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UPDATE: I took my LS to Best Buy finally and the people from Geek Squad couldn't figure it out either $80.00 later. Apparently the remote start sequence works more often when the car is in virtual tach mode rather than just tach sense mode. He used the Bitwriter tool to program the system to only crank for 0.6 seconds no matter what. The car still continued to crank indefinitely even with it set to ONLY crank for 0.6 seconds. He thinks that it might be faulty. HE also checked all of the remote start connections and soldered a few.

(Final UPDATE) I finally figured out the problem with the old 94 LS. the tach signal behind the instrument cluster worked perfectly and no hood pin was needed. All of the wires were connected properly to begin with. The system is set to tach sense for the remote start. Also, no bypass was needed for the security system. The problem was actually in the electrical ignition switch. Some of the contacts inside were touching where they weren't supposed to be which caused the starter to crank indefinitely. I was able to recreate the indefinite cranking by using a flat head screw driver to manipulate the switch in different directions once I removed it from the back of the lock cylinder. I took it apart and cleaned it and now my remote start works as it should!! Here's a picture of the part.