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Juan Crespo
Juan Crespo, ASE Certified Technician
Category: Chevy
Satisfied Customers: 1516
Experience:  A.S.E. Master Technician, Advanced Level, Emissions - Asian, Domestic, & European
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I removed my viper alarm, now my truck won't start. Turns

Customer Question

I removed my viper alarm, now my truck won't start. Turns over, has fuel, but won't start.
Submitted: 7 months ago.
Category: Chevy
Customer: replied 7 months ago.
This is not a dodge, a 2006 chevy silverado 2500 hd, allison
Expert:  chevygeorge replied 7 months ago.
Hello. it's likely this alarm interrupted the ignition circuit of your vehicle and when you removed it from your system you left an open circuit in your ignition circuit. Do you know the model number of your Viper alarm? Did you have any addition loose wires after you removed it?
Customer: replied 7 months ago.
I didn't see any other loose wires. I hooked it back up, it starts with remote start. But it won't override with the key.
Expert:  chevygeorge replied 7 months ago.
Are you merely unplugging the connector to the alarm? Do you have a model number for the alarm?
Customer: replied 7 months ago.
I believe the alarm is a viper 5704, I actually cut all the wires going to and from the alarm box. Long enough to reconnect them if necessary. I think you have the right answer, there must be an ignition wire that is now part of the alarm system.
Expert:  chevygeorge replied 7 months ago.
Yes, there should be a wire they cut and one side went into the alarm and one side came out of the alarm that spliced to the other of the wire. Probably a purple wire, but give me a second to pull up the diagram.
Expert:  chevygeorge replied 7 months ago.
It should breakout and return from a factory harness. The wiring schematic should be on the alarm module, as it's not in the manual.
Expert:  chevygeorge replied 7 months ago.
Actually, it appears to be pink.
Customer: replied 7 months ago.
I am not at the truck till Wednesday, I will check then. The wiring isn't on the module. I do know that.
Expert:  chevygeorge replied 7 months ago.
Okay.
Customer: replied 7 months ago.
Well, I looked at the wiring again today. Doesn't appear to be aNY disconnected wires, with the exception of the yellow wire.
Customer: replied 7 months ago.
I reconnected it, still not working.
Customer: replied 7 months ago.
I know there must be spark wire disconnected somewhere
Expert:  chevygeorge replied 7 months ago.
I'm sure you're on the right track, we just need to find the all the wires. I'm going to go ahead and opt out so we can get your question back out there so it will be seen by other experts more familiar with your particular alarm. Best of luck. George
Expert:  mike switzer replied 7 months ago.
you said it starts with the remote start but not with the key?
Expert:  mike switzer replied 7 months ago.
if so when you use the key and turn the truck to the on position does the security light come on then shut off.
Customer: replied 7 months ago.
At this point, I have completely removed the alarm. So, the remote start is no longer connected. It appears that all of the wires except one were "saddle" connections. The only one that I saw that was not, was the yellow wire going to the starter, it had been cut with both ends going to the alarm. I connected them back, the starter turns over, the fuel pump runs, but the engine won't fire. I think there must be a wire to the coil that has been interrupted.
Customer: replied 7 months ago.
Or I have seen on utube, sometimes there is a relay installed.
Expert:  chevygeorge replied 7 months ago.
I just had a thought. This alarm has a separate remote start module. It will interface with the BCM to provide remote start similar to what the factory has. I assumed these modules were installed near each other. Did you remove both modules? I had a schematic but it was too large to send. Let me resize it and send it to you. There are about 4 alarm brand that are just rebranded 5704's. I was thinking you may be not getting injector firing, rather than spark control issue. The BCM gives the ok to fire the injectors if all security criteria are met.
Customer: replied 7 months ago.
I purchased the original alarm and had it installed, there was only one control box.
Expert:  Juan Crespo replied 7 months ago.
Hi there. Yet another expert trying to help...I might be able to help, but first I need you to answer a few questions for me:What engine is in your truck? If it burns gasoline, what's missing that it won't start; compression, fuel pressure, injection pulse or ignition spark? If diesel, will it start with penetrating oil or starting fluid? Is the OEM Security light on the dash illuminated?
Customer: replied 7 months ago.
Hello, and thanks for the response. It is a 5.7 gas, throttle body injection. There is no security light, it's a '95 Chevy Silverado. 3/4 ton***** It used to start with the alarm installed, so it isn't an engine fail issue. It has to do with removal of the alarm. At one point I put the alarm back in, and the truck would start and run. I no longer the want the alarm, so I have uninstalled it, and now trying to get the engine to start.
Expert:  Juan Crespo replied 7 months ago.
I understand and thank you for the information. However, I still need you to answer these two questions before I can formulate an effective diagnosis:What's missing that it won't start; compression, fuel pressure, injection pulse or ignition spark?Will it start with starting fluid?
Customer: replied 7 months ago.
There is no OEM security light on this model. It wouldn't be compression. The fuel pump runs, so, I am guessing fuel is available. I believe it is ignition spark, going to check that tonight.
Expert:  Juan Crespo replied 7 months ago.
That information will point me in the direction of whatever circuits are open or affected by the install and removal of the Viper alarm. Please let me know as soon as you can so we can continue. I'm online weekdays from 2 to 8 PM EST.Best Regards.
Customer: replied 6 months ago.
After talking with the original installer, and information received from an online forum, it turns out the issue is not with the alarm. The truck starts and runs. Still have issue though. Now, sometimes while the truck is running, if you turn on the left turn signal, or step on the brake, it will kill the engine. And here is another "kicker", it doesn't always happen. Also, when observing the dash mounted volt meter, while turning on the key, it shows 14+ volts, while cranking it drops to a little under 14. If while cranking the volt meter drops to zero, the engine still turns over, but it will not start. If it doesn't drop to zero, the engine will start.

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