Speedometer issues at idle - other electrical oddities

pjkinsella

Enthusiast
Joined
Apr 21, 2016
Posts
21
Reaction score
0
Hey guys, new guy here.

I just acquired a 98 Viper GTS (King Snake) that's had a ton of work done to it over the years, so I know this may be a difficult one to answer definitively, but I'm just looking for some ideas of things to look for.

Weird things that are happening:
- Speedometer is fluctuating around 40 mph at idle (and yes that means odometer is ticking up!). When the car is moving, it seems to be working fine.
- The left turn signal (dash light) is faintly lit.
- After the car heated up, the shift light came on and stayed on (aftermarket, obviously).
- The oil light came on.
- The car will not idle until it's warmed up (this may or may not be related).

This has an aftermarket AEM ECU, but also still has the factory computer. That means there's extra wiring everywhere, so I have a lot to sort through. This car has been sitting for a while, but when I bought it a week ago, everything seemed to be normal.

My initial thought was that it's a low power, or high amp draw, issue (if you've been in a car that almost completely loses electrical power, everything just goes haywire). But it could also be a wire that rattled loose, or was mostly chewed in half by a mouse.

A ton of variables, I know, but if anyone has any experience with something like this and might have a few pointers on where to start, I'd really appreciate it!

Also, yes I cross-posted this on "another" forum. :nono:
 

Steve-Indy

VCA Venom Member
Venom Member
Joined
Oct 2, 2000
Posts
8,536
Reaction score
171
Location
Zionsville,IN. USA
First thought would be dying battery...very common. Check voltage before attempting to start. After that, all wiring added on is suspect...especially the AEM in my opinion. It is also smart to check wires coming off of battery, motor grounds, and O2 sensor wires if you have headers. Good hunting.
 
OP
OP
P

pjkinsella

Enthusiast
Joined
Apr 21, 2016
Posts
21
Reaction score
0
Steve, I think we're on pretty much the same page. I put a voltmeter on it today and it read about 12.4v. I know that's a little low, but low enough? Not sure.

And I'm in Louisville, KY!
 

Free2go

Enthusiast
Joined
Aug 11, 2013
Posts
3,290
Reaction score
6
I heard those King Snake cars were pretty bad ass. The Terpstra brothers (TNT) built them before they were shut down by Hennessy. As a matter of fact, my wife was studying what constitutes trade secrets in one of her law school classes and the professor brought up their case.
 
OP
OP
P

pjkinsella

Enthusiast
Joined
Apr 21, 2016
Posts
21
Reaction score
0
I heard those King Snake cars were pretty bad ass. The Terpstra brothers (TNT) built them before they were shut down by Hennessy. As a matter of fact, my wife was studying what constitutes trade secrets in one of her law school classes and the professor brought up their case.

Yeah I'd really like to know what happened to them, honestly.

By the way, this car is King Snake serial number 002, which is pretty cool.

A lot of work has been done to this car even after the King Snake package though.
 

Steve-Indy

VCA Venom Member
Venom Member
Joined
Oct 2, 2000
Posts
8,536
Reaction score
171
Location
Zionsville,IN. USA
Agree that is a little low...but, may not tell the whole story. What does it do with a load, and how does it charge? I will admit that I try to stay well ahead with an older battery...changing it before it bites me. Give me a call for tech info in Louisville. 317-402-9013
 

Steve-Indy

VCA Venom Member
Venom Member
Joined
Oct 2, 2000
Posts
8,536
Reaction score
171
Location
Zionsville,IN. USA
Do you have a 1998 Service Manual? One problem with it is that an occasional diagram is carried over from Gen I...and, can be quite misleading.
 

TalonTSi90

Enthusiast
Joined
Jun 29, 2016
Posts
612
Reaction score
0
Top