ScanGauge Failures Resolved?

[brucepick]

Has anyone had trouble with their SG losing it's OBDII Mode setting or losing it's accumulated data? That's what mine was doing. Since about last November or so. It's been a long time.

The SG people replaced the board twice and also provided a second connecting cable. After the 2nd board replacement gave no improvement I decided it mustbe due to something going on with the car, not the Scangauge.

I think I finally resolved it by isolating two power hungry circuits from the power bus that provides 12V to the OBDII port. The horn and headlights now get power separately from the battery and not via the maze of 18-22 ga. wires in the oem harness.

I installed a very heavy (8-10 ga.) tap off the battery to a new junction box that feeds power to three relays, each via a separate fuse. All the other added wiring is minimum 14 ga., some are heavier. One relay powers the horn, the other two power the high and low beams respectively. Each relay is triggered by the wire that formerly ran the horn or headlight. In the case of the headlight relays, they're run off the passenger side headlight socket. All relays I installed are fitted with diodes across the relay coil terminals, intended to eliminate the strong back EMF that can occur when the coil's field collapses after power is cut. (google it or ask me if you need details on that last bit)

Today after completing the last of the headlight relay installation I made extensive use of the horn and both high and low beams and flash function. The ScanGauge didn't fail even once. My commute is 50 miles each way. Since it was rainy I also was running the wipers and intermittently the a/c compressor and blower fan so I think I taxed the system pretty well.

Anyone else have problems with a ScanGauge failing mysteriously?

[RobertSmalls]

Half of the plastic tabs that hold my car's OBD-II connector in place were broken, so I had a poor connection. If you bumped the cord wrong, the SG would sometimes flicker on and off, and sometimes lose its memory. So I broke the rest of the plastic tabs off, and zip-tied the connector in place under the dashboard. I haven't had a problem since. Glad to hear you got your issue resolved, too.

[brucepick]

Hmm, plastic tabs? I should go look under the dash and see what mine look like. It feels pretty solid plugging in though. Thanks for mentioning those.

[brucepick]

bump

Anybody else had a ScanGauge failure?

[NiHaoMike]

I don't have a Scangauge (yet), but how about add a large 2F car A/V capacitor?

[brucepick]

"large 2F car A/V capacitor" means??

Actually a friend suggested:
1000µF, 160 mOhm series resistance, and 21 mm diam x 38 mm. in size, priced just under $10 each plus shipping.

To be put across the 12V+ and ground wires at the OBDII connector. I took one look under there and decided I didn't want to try performing surgery in that tight area which also leads directly back to the computer. So I built the relay circuits which I was confident I could do without causing trouble, and get improved lighting and horn output also.

[FastPlastic]

My scangauge seems to be lazy sometimes. Not always kicking on when I start the car. So it tends to be 5-7miles off when I go to fill up the tank. Happens more often when I do a lot of little trips.

[Ricketts]

The only issue I had was just this week removing it from my Saturn to install in my truck. The RJ45 plug was jammed, and unknowingly I pulled the whole plastic retainer out of the back of the scangauge. I bent one of the leads, but managed to straighten it and snap the retainer back into the back of the scangauge.

I guess if you are removing it often from your vehicle it could be something to watch out for.

Other than that it has been good.

Rick

[PaleMelanesian]

I've not had any trouble with mine, on a similar year/model car as yours. Could something be different with the HX than the DX I have? I'm curious about the success of your fixes, though.

[brucepick]

Originally Posted by PaleMelanesian

I've not had any trouble with mine, on a similar year/model car as yours. Could something be different with the HX than the DX I have? I'm curious about the success of your fixes, though.

I've just completed over 400 miles since completing the relays project - no more ScanGauge failures. (100 mi. round trip commute adds up quickly when car pool buddy is out for a few days)

I've been wondering if maybe a previous owner hacked (um, deliberately modified) the wiring or electrical system in some way. Or if possibly the car was in an accident that compromised the electrical - possibly a bad ground or other issue. Sorry, I don't have a CarFax account and I'm not keen on coughing up the money to go investigating. Just considering the possibility that it might not be a car design/manufacturing issue, but something that occurred afterwards.