Factory Five Racing Forum banner
1 - 20 of 27 Posts

· Registered
Joined
·
228 Posts
Discussion Starter · #1 ·
Guys,

I am at my wits end with this issue and am finally posting here after being on the12volt.com forum.

I am installing a Viper 5704(update 5901) alarm and RS. Installed multiple units with no issues.

I will not go into all the details but will summarize here:

2 way and 1 way remote will not communicate with brain when car is running. (IE pit stop mode will not work, cannot 'unlock' doors :/ with remote start active)

Grounds:
Battery to frame
Engine to frame
RF harness to frame
EFI harness to engine

I have tried a lot of troubleshooting already and have found the following:

Disconnected MSD 6al with no improvement.
disconnected all wires to alarm minus 12V+ and ground. no comm

I did hook the alarm up to a spare battery, set it in trunk and started car. I got comm with remote engine was running. I believe this helps rule out RF interference.


I can pull the positive battery cable and EFI power supply from battery while car is running and I get comm. If I pull just the main battery cable and leave the EFI harness connected to battery, I get no comm with remote.

Here is a link to the thread I started on the12volt.com

viper 5704 comm issue

If yall have patience I would appreciate yall read it and see if yall can gather anything from it.

I have a crisp $20 bill ready to mail to the person that has the answer!!!


Thanks,
Tyler
 

· Registered
Joined
·
1,182 Posts
I didn't read the other post that you linked, but are you saying that the remote works fine when the car is not running but does not work when the car is running? If so, check the power source for the unit itself. If you're only feeding it with a circuit that is not "hot in run" then you'll need to add a feed.
 

· Registered
Joined
·
523 Posts
Had an issue with a Viper similar to yours, turned out to be a bad main control unit, which the tech at Viper stated "never happens" :001_rolleyes:


Bill S.

I agree with Bill, swap in another unit to rule out bad brain.
I've put in many alarms/ remote start units and I bet 1 out of 7 was junk.
 

· Registered
Joined
·
228 Posts
Discussion Starter · #10 ·
By control center do you mean brain or antenna with light and button?

I initially had the brain behind dash, but now have directly hooked up to battery, a foot away.

The antenna (Which i think is the control center), I have moved around from the bulkhead, mounted to my body buck, on the ceiling, anywhere away from the electrical interference sources....
 

· Registered
Joined
·
1,340 Posts
Sorry, I have been working through your post on 12volt and saw the answer so I deleted my post not realizing you had responded. Yes, I was refering to the brain.

I'm a EE during the day and from the symptoms you describe, it sounds like an interference issue but it seems to be coming from the power line rather than through RF. I base this on your observation that it works properly when you use a 2nd battery to power the unit. This makes me believe you are getting noise on the power line which is confusing the brain. I would try installing line filters (capacitors) on all of the power wires going into the brain.

I am still reading your 12V post so I will come back if I see anything else.

Todd

By control center do you mean brain or antenna with light and button?

I initially had the brain behind dash, but now have directly hooked up to battery, a foot away.

The antenna (Which i think is the control center), I have moved around from the bulkhead, mounted to my body buck, on the ceiling, anywhere away from the electrical interference sources....
 

· Registered
Joined
·
1,340 Posts
Before you move into anything exotic like a power stabilizer, you should try to isolate the power lines with a noise filter like those used for car amps.

American International S-15A (15-amp/250-watt) Power line noise filter at Crutchfield.com

Crutchfield has a couple of options that will do this. You may end up needing 2 (1 for the line going to the battery and another for the switched line going through the ignition) but I would start with one and run all incoming power to your brain through it just to see if this solves the issue.

The brain isn't a high current device so you don't need a big amp rating. The S-15A at the link above should be more than enough to cover your needs.

I didn't dig deep into the link you provided but the front page is all RF shielding material which doesn't seem to be the source of your problems.

HTH
Todd

Sorry, I have been working through your post on 12volt and saw the answer so I deleted my post not realizing you had responded. Yes, I was refering to the brain.

I'm a EE during the day and from the symptoms you describe, it sounds like an interference issue but it seems to be coming from the power line rather than through RF. I base this on your observation that it works properly when you use a 2nd battery to power the unit. This makes me believe you are getting noise on the power line which is confusing the brain. I would try installing line filters (capacitors) on all of the power wires going into the brain.

I am still reading your 12V post so I will come back if I see anything else.

Todd
 

· Registered
Joined
·
228 Posts
Discussion Starter · #13 ·
I agree that my test of the separated circuit to power the alarm while the car was running ruled out RF interference. I did wire in a 1uF cap in parallel to the brain with no benefit. I will pick up a noise filter to see how that affects it.

Thanks
 

· Registered
Joined
·
926 Posts
I hate to say this, but I’m on board with Bill here :sad:. I installed a Viper unit on my 70 Chevy and sure enough, it was like yours and had about the same problem. I got with the reps for the unit and they sent me a new unit (because it couldn’t do what it was doing) and that fixed the problem. I’ve had it installed for a while now with no troubles since.
 

· Registered
Joined
·
1,340 Posts
I thought I read in his other post that he swapped this unit out with a known good unit and it didn't solve the issue....

I hate to say this, but I’m on board with Bill here :sad:. I installed a Viper unit on my 70 Chevy and sure enough, it was like yours and had about the same problem. I got with the reps for the unit and they sent me a new unit (because it couldn’t do what it was doing) and that fixed the problem. I’ve had it installed for a while now with no troubles since.
 

· Registered
Joined
·
1,340 Posts
I agree that my test of the separated circuit to power the alarm while the car was running ruled out RF interference. I did wire in a 1uF cap in parallel to the brain with no benefit. I will pick up a noise filter to see how that affects it.

Thanks
Yeah, I saw that in your other post. I've never been a big fan of the straight capacitor approach. It can work but you need to calculate the right size cap to get it right. If this is your problem, it is much easier to just buy a proper filter that will clean up the noise.

Based on your description of the symptoms (works when battery and EFI are disconnected but not when just the battery is disconnected) I suspect that the noise is coming from your EFI system but I would also check to see if it is coming from the voltage regulator in your alternator by disconnecting the wire(s) from the alternator and retesting the system. Regardless, if it is noise, the easiest thing is going to be simply filtering it.

HTH
Todd
 

· Registered
Joined
·
181 Posts
What type of plug wires are you using? Some plug wires (especially older designs) emit a tremendous amount of RF energy in a wide frequency spectrum. I remember from a RF communication course years ago that the pulse nature of the spark signal is the worst type for electrical noise.

Maybe all new plug wires are designed to suppress RF, I am not sure, but it is something to check into.

Dennis
 

· Registered
Joined
·
228 Posts
Discussion Starter · #18 · (Edited)
What type of plug wires are you using? Some plug wires (especially older designs) emit a tremendous amount of RF energy in a wide frequency spectrum. I remember from a RF communication course years ago that the pulse nature of the spark signal is the worst type for electrical noise.

Maybe all new plug wires are designed to suppress RF, I am not sure, but it is something to check into.

Dennis
I am using Spiro core Taylor wires.

Ok so I just tried a PAC 12 amp noise filter. Wired in line to the 5704, no luck. Tried the 5901, no luck....about to chalk this one up as a loss..

FYI only 14 gauge power and ground hooked up, nothing on RS harness.

also I disconnected the plug from my 3G alternator to test with no charging in the system...no luck.
 

· Registered
Joined
·
1,340 Posts
I am using Spiro core Taylor wires.

Ok so I just tried a PAC 12 amp noise filter. Wired in line to the 5704, no luck. Tried the 5901, no luck....about to chalk this one up as a loss..

FYI only 14 gauge power and ground hooked up, nothing on RS harness.

also I disconnected the plug from my 3G alternator to test with no charging in the system...no luck.
OK, here is what I expect is going on.

First, it would appear that the problem is being caused by your EFI circuit. By disconnecting the alternator you have removed the charging system as the point of interference and by swapping out the viper, you have removed it as the likely cause. The fact that the system works when you disconnect the EFI and Main connections to the battery but fails if the EFI is connected points towards the EFI. You described that you have the battery connected to the frame and the engine also connected to the frame but I suspect you are still chasing a ground loop issue being caused by the EFI controller. The EFI system will pull quite a bit of power since it is driving the coil as well as pulsing 8 injectors and managing a pile of sensors. This load can create a variance in the power plane that could cause your viper to misbehave. The easiest way to confirm this would be to use a decent gauge of wire and run the EFI ground all the way back to the battery. If a ground loop is the problem, this will ensure that the EFI controller has the best possible ground which would clear up any resulting grounding issue. I would try this as your last resort before you give up.

HTH
todd
 
1 - 20 of 27 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top