OBDII Wire Gauge (1998 v70 non turbo)

Post by **MrAl** » 04 Feb 2023, 07:25

Hello there,

Does anyone know what the wiring gauge (AWG) to the OBDII connector is for this car?
It would be best to state in AWG units (American Wire Gauge).

I need to know for the purpose of light charging through the OBDII connector. I may turn to more direct wiring to the battery in the future but im not going to attempt that until it gets a bit warmer out there. I also do not want to use the aux connector under the dash somewhere (forgot where that is again ha ha) even if i remember where it was.

Post by **scot850** » 04 Feb 2023, 08:04

I can't answer that for you, but funnily I wa talking to my brother in Denver about his 97 850 on the same subject. He pointed out the cigarette lighter outlet is switched so connecting the solar charger to there does not work for a back feed to the battery. He is now going to run a wire direct to the battery under the dash instead with a quick coupler.

Neil.

454cid · Post by **454cid** » 04 Feb 2023, 15:08

scot850 wrote: ↑04 Feb 2023, 08:04 I can't answer that for you, but funnily I wa talking to my brother in Denver about his 97 850 on the same subject. He pointed out the cigarette lighter outlet is switched so connecting the solar charger to there does not work for a back feed to the battery. He is now going to run a wire direct to the battery under the dash instead with a quick coupler.

Neil.

I was just thinking of this yesterday. I noticed this myself when I've had my phone plugged into the car.

Post by **MrAl** » 05 Feb 2023, 03:23

scot850 wrote: ↑04 Feb 2023, 08:04 I can't answer that for you, but funnily I wa talking to my brother in Denver about his 97 850 on the same subject. He pointed out the cigarette lighter outlet is switched so connecting the solar charger to there does not work for a back feed to the battery. He is now going to run a wire direct to the battery under the dash instead with a quick coupler.

Neil.

Hi Neil,

Yes that was both a blessing and a curse for me when i was using my analog volt meter to keep an eye on the battery during starts and general running to verify the charging process.

It was a blessing because when i switched the ignition off, the meter went off, so no drain on the battery (even though kind of small anyway).
It was a curse because i could not monitor the drop in voltage when the car was first being started, which is a good indication of how the battery is doing. I had to go to the OBDII connector for that and that was harder to do i had to buy a connector and wire it up and all. In the old Hyundai i had it wired direct to the battery (with fuse). I intend to do that with the Volvo too hopefully soon. I put it off for a couple years now but now with the solar panel it's more of a necessity.

If you can find out more about his setup that would be nice too i'd be interested to hear how he is doing it and what kind of panel and if he uses a controller and if so what kind of controller (max power point or just boost converter for two examples).
I guess that would also include how many hours of sun do they get there.

Post by **P80GLT** » 05 Feb 2023, 05:07

With your multi-meter you should be able to determine which wire on your radio plug is 12v + permanently

Post by **scot850** » 05 Feb 2023, 07:22

The radio has 2 permanent wires and 1 switched, + a small pink one for the instrument lighting control. I will check later on the colors of the 2 permanent power wires. They are green/something but I will confirm.

Al, I will find out from my brother how he sets up and how successful his system is. It may be a while as he is typically short of spare time.

Neil.

Post by **scot850** » 05 Feb 2023, 13:27

Ok, as promised. Here is a picture of one of my connector pigtails for the Volvo P80 radios. This is the larger of the 2 black block connectors:

: Radio harness large block power wires.; PXL_20230205_205112056.jpg (185.26 KiB) Viewed 195 times

So top wire (Yellow/Violet is the switched power from the ignition switch to the radio.

Middle 2 wires (brown/Green) are the constant power lines

Lowest wire (Pink) is the dashboard illumination control for the brightness.

There are also 2 black wires (grounds) that are joined together.

Hope this helps.

Neil.

Post by **MrAl** » 11 Feb 2023, 08:14

Hello again,

Ok back to the OBDII wire gauge for this car.

I found this image posted by RickHaleParker some time back around 2019.
It shows the #16 wire, which is the +12v wire, going back to the fuse labeled as "C5". I looked at my fuse layout on my car and it says it is just "5" but it also says "Diagnos" which i assume is short for "Diagnostics".

The really interesting part though is that the fuse is rated for 15 amps. That suggests that the wire gauge should be #16 AWG or better, like #14. I will check into this further but that sounds right. That would mean the #16 pin could, in theory, handle at least 10 amps.
That's surprising to me because i was thinking it might be #22 AWG because it's only for signal transmission and a little power for OBDII meters, but maybe Volvo was smart enough to oversize the wire for better durability.

Diagram follows...