Ground Loop

Ground Loop

Postby raycer [OP] » February 3rd 2009, 6:03pm

I've been installing a Nordsdok Digital Gauge Panel and it all went well untill I hooked up the speedo. This is installed in a 1989 Cargo with a 1989 TBI 350 V8 hooked up to a 700R4 tranny that has a VSS.
I've been talking to tech support and they are asking to make sure I don't have more than one "Ground Loop" in my electrical system. As far as I know, the way I have the ground hooked up is: the battery ground is tied to a bolt on the body at the radiator support, then goes from there to a bolt on the intake manifold.

The problem is that sometimes while being at a stop, the speedo starts to show speed numbers and then goes back to cero. The tech guy says it's more then likely a grounding problem. That there should be only one "Ground Loop".
The biggest problem is: I DID THE MOTOR SWAP!! :whack: so of course I don't know any specs on how it was done!! to much :cheers: if you know what I mean.

Any advise on what I'm missing?
Original Poster [OP]
User avatar
raycer
V8 Swap Achievement
V8 Swap Achievement
Firing on 2 Cylinders (L1)
Firing on 2 Cylinders (L1)
Years of Membership: raycer has been a member for 12 full yearsraycer has been a member for 12 full yearsraycer has been a member for 12 full yearsraycer has been a member for 12 full yearsraycer has been a member for 12 full yearsraycer has been a member for 12 full yearsraycer has been a member for 12 full yearsraycer has been a member for 12 full yearsraycer has been a member for 12 full yearsraycer has been a member for 12 full yearsraycer has been a member for 12 full yearsraycer has been a member for 12 full years
Posts: 238
Topics: 16
Joined: February 2008
Location: Houston, Texas
Gender: Male
Alias (AKA): ray
Van Make/Model: Chevrolet Astro
Extra Info: 1989 TBI350

  • Similar topics
    Replies
    Views
    Author
  • Where are the ground straps on 1997 GMC Safari Van?
    by K-TRON » September 28th 2020, 6:51am in Electrical
    3 Replies
    216 Views
    Last post by K-TRON View the latest post
    September 29th 2020, 9:07pm
  •  
    10
    57
    Last post by AstroSafari.com View the latest post
    November 28th 2020, 12:04pm

Re: Ground Loop

Postby astro355 » February 3rd 2009, 9:35pm

That does sound like a ground problem. Don't you have a main ground cable going from the battery to the engine block?
Diagnose 1st, never be a parts changer!

355 small block chevy w/ modified 700R4

Image
User avatar
astro355
V8 Swap Achievement
V8 Swap Achievement
Firing on 4 Cylinders (L6)
Firing on 4 Cylinders (L6)
Years of Membership: astro355 has been a member for 12 full yearsastro355 has been a member for 12 full yearsastro355 has been a member for 12 full yearsastro355 has been a member for 12 full yearsastro355 has been a member for 12 full yearsastro355 has been a member for 12 full yearsastro355 has been a member for 12 full yearsastro355 has been a member for 12 full yearsastro355 has been a member for 12 full yearsastro355 has been a member for 12 full yearsastro355 has been a member for 12 full yearsastro355 has been a member for 12 full years
Posts: 5484
Topics: 57
Joined: May 2008
Location: Cleveland, OH
Gender: Male
Alias (AKA):
Van Model Year: 1989
Van Make/Model: Chevrolet Astro
Extra Info: 355 V8 700R4

Re: Ground Loop

Postby 'cudapaul » February 4th 2009, 12:54am

That doesn't sound like a ground problem to me.
I think it might be picking up electrical noise or ignition (spark plug) noise that is being radiated into the speed sensor leads or DRAC output.

I have seen instances where reving the engine in an Astro/Safair with the factory digital dash will cause the speedometer to read a few miles per hour and go back to zero at idle.

The speedo counts pulses and having a issue with a bad or poor ground, I thnink, would cause the gauge to either not work, change brightness, or read wrong at all speeds. But you might also be fighting an inherent design problem in the vehicle wiring since I have seen the factory digital do the same thing.

There is no easy solution since the VSS in the trans feeds a module (DRAC, Digital Ratio Adapter) in the dash that cleans up and divides the output of the VSS into pulses that go to the ECM, cruise control, and speedometer. The only solution I could suggest would be to try a replacement DRAC module or change the VSS sensor. And probably none of them will positivley cure it.
'cudapaul
AstroSafari Pioneer
AstroSafari Pioneer
Firing on 5 Cylinders (L1)
Firing on 5 Cylinders (L1)
Years of Membership: 'cudapaul has been a member for 12 full years'cudapaul has been a member for 12 full years'cudapaul has been a member for 12 full years'cudapaul has been a member for 12 full years'cudapaul has been a member for 12 full years'cudapaul has been a member for 12 full years'cudapaul has been a member for 12 full years'cudapaul has been a member for 12 full years'cudapaul has been a member for 12 full years'cudapaul has been a member for 12 full years'cudapaul has been a member for 12 full years'cudapaul has been a member for 12 full years
Posts: 596
Joined: January 2008
Gender: Male
Alias (AKA): 'cudapaul
Van Make/Model: Chevrolet Astro
Extra Info: LT AWD

Re: Ground Loop

Postby astro355 » February 4th 2009, 5:40pm

'cudapaul wrote:
I have seen instances where reving the engine in an Astro/Safair with the factory digital dash will cause the speedometer to read a few miles per hour and go back to zero at idle.

And that is because there is not "enough" of a ground to cover the system.
'cudapaul wrote:The speedo counts pulses and having a issue with a bad or poor ground, I thnink, would cause the gauge to either not work, change brightness, or read wrong at all speeds. But you might also be fighting an inherent design problem in the vehicle wiring since I have seen the factory digital do the same thing.

There is no easy solution since the VSS in the trans feeds a module (DRAC, Digital Ratio Adapter) in the dash that cleans up and divides the output of the VSS into pulses that go to the ECM, cruise control, and speedometer. The only solution I could suggest would be to try a replacement DRAC module or change the VSS sensor. And probably none of them will positivley cure it.

If you completely remove the ground, the gauge will spike, not stop working. I would stick with the tech's advise here.
Diagnose 1st, never be a parts changer!

355 small block chevy w/ modified 700R4

Image
User avatar
astro355
V8 Swap Achievement
V8 Swap Achievement
Firing on 4 Cylinders (L6)
Firing on 4 Cylinders (L6)
Years of Membership: astro355 has been a member for 12 full yearsastro355 has been a member for 12 full yearsastro355 has been a member for 12 full yearsastro355 has been a member for 12 full yearsastro355 has been a member for 12 full yearsastro355 has been a member for 12 full yearsastro355 has been a member for 12 full yearsastro355 has been a member for 12 full yearsastro355 has been a member for 12 full yearsastro355 has been a member for 12 full yearsastro355 has been a member for 12 full yearsastro355 has been a member for 12 full years
Posts: 5484
Topics: 57
Joined: May 2008
Location: Cleveland, OH
Gender: Male
Alias (AKA):
Van Model Year: 1989
Van Make/Model: Chevrolet Astro
Extra Info: 355 V8 700R4

Re: Ground Loop

Postby raycer [OP] » February 4th 2009, 7:02pm

yeah, I need to make sure my ground loop is sound. My ground cable goes from the battery to the body and from there to the engine intake manifold. I'm gonna make sure I go from the battery onto the engine block and from there to the chassis and from there to the body.

The motor mounts are isolated by the rubber bushing, correct?

Thanks for the help guys.
Original Poster [OP]
User avatar
raycer
V8 Swap Achievement
V8 Swap Achievement
Firing on 2 Cylinders (L1)
Firing on 2 Cylinders (L1)
Years of Membership: raycer has been a member for 12 full yearsraycer has been a member for 12 full yearsraycer has been a member for 12 full yearsraycer has been a member for 12 full yearsraycer has been a member for 12 full yearsraycer has been a member for 12 full yearsraycer has been a member for 12 full yearsraycer has been a member for 12 full yearsraycer has been a member for 12 full yearsraycer has been a member for 12 full yearsraycer has been a member for 12 full yearsraycer has been a member for 12 full years
Posts: 238
Topics: 16
Joined: February 2008
Location: Houston, Texas
Gender: Male
Alias (AKA): ray
Van Make/Model: Chevrolet Astro
Extra Info: 1989 TBI350

Re: Ground Loop

Postby astro355 » February 4th 2009, 8:04pm

You don't have to worry about that. There are several places were the engine wiring harness grounds to the block but you need the big ground cable going from the battery to the block. You really shouldn't be able to start your van without that ground.
Diagnose 1st, never be a parts changer!

355 small block chevy w/ modified 700R4

Image
User avatar
astro355
V8 Swap Achievement
V8 Swap Achievement
Firing on 4 Cylinders (L6)
Firing on 4 Cylinders (L6)
Years of Membership: astro355 has been a member for 12 full yearsastro355 has been a member for 12 full yearsastro355 has been a member for 12 full yearsastro355 has been a member for 12 full yearsastro355 has been a member for 12 full yearsastro355 has been a member for 12 full yearsastro355 has been a member for 12 full yearsastro355 has been a member for 12 full yearsastro355 has been a member for 12 full yearsastro355 has been a member for 12 full yearsastro355 has been a member for 12 full yearsastro355 has been a member for 12 full years
Posts: 5484
Topics: 57
Joined: May 2008
Location: Cleveland, OH
Gender: Male
Alias (AKA):
Van Model Year: 1989
Van Make/Model: Chevrolet Astro
Extra Info: 355 V8 700R4


 
  • Related topics
    Replies
    Views
    Last post

Return to Electrical

It is currently November 28th 2020, 12:04pm

Electrical Forum
ElectricalDiscussion specific to electric components of vans. Category for alternators or batteries, starters and ignition parts, anything 12v and electrical issue like fuses, circuitry, wire, terminals, switches, connectors, bulbs, relays, and wiring. Voltage and amperage diagnosis.
To create a new topic in Electrical, click this button:
Previous topic Next topic
Recent Image Attachments
Attached by:
Dbleeger
in Electrical
Views: 148
Comments: 13
Date: Yesterday
Time: 11:29pm
» Read last comment
Attached by:
tungtide
in Electrical
Views: 138
Comments: 10
Date: Nov 23 '20
Time: 4:40pm
» Read last comment
Attached by:
Attached by: stent
stent
in Electrical
Views: 934
Comments: 24
Date: Nov 20 '20
Time: 8:18am
» Read last comment
Attached by:
Attached by: sixsix
sixsix
in Electrical
Views: 276
Comments: 12
Date: Nov 20 '20
Time: 1:16am
» Read last comment
Attached by:
Attached by: AstroWill
AstroWill
in Electrical
Views: 276
Comments: 12
Date: Nov 19 '20
Time: 8:00pm
» Read last comment
Sponsors

Who is online

Users browsing this forum: No registered users and 8 guests