Anks329 - Extended City - '07 LS - #190 REGISTERED

CaptFrank2001

Well-Known Member
There is a quick way to check your grounds. You need a multi-meter. First hook both leads to you battery (plus & minus) & check the voltage. Should be around 12.8 volts of so. Now remove the negative lead only and attach it to wherever your grounds attach to the frame. You should see the same 12.8 volts or maybe a little less. If it's 12.4 volts or lower you have a ground problem. Whatever you battery voltage is, a loss of .3 or .4 volts is a problem. If your car does run you should do these checks first without the car running then start the car and check them all again. Good luck.
 

SACTX

Well-Known Member
One thing I’m not seeing in that diagram is a connection to the ECM. The ECM transmits the rpm and speed data to the BCM. I'm sure it's different than mine but you can check. Mine is on ECM C1 Pin 16. Check continuity from any other low speed data line to that one if you're not getting any engine stuff but are getting communication with the Driver Info System.
 

Attachments

Anks329

Well-Known Member
Ok, tested grounds last night. 12.53v across the battery terminals, and 12.53v between the IPC ground, IPC signal ground, OBD ground, and I checked the ground by the battery and the ground on the pedal box just to check. 12.53v across all of them. I've got continuity between the the grounds mentioned here and the ground lugs as well on the frame.

Tonight, I'll find a way to ground the screw hole on the back of the BCM. And check the continuity from the ECM. Although, I should have continuity here as I'm able to see pull the relevant info through the OBD reader that I have.
 

SACTX

Well-Known Member
I forgot about being able to see it on the scanners. That means you're good to the ECM. Grounds are good. You've got green wire continuity from BCM to Cluster. The cluster is getting power.

I don't know what else to check....
 

Anks329

Well-Known Member
Sigh, I’ve grounded the back BCM, I’ve tested grounds, continuity of data wire, and the power wire. All seems to check out, but the gauges are still not displaying rpm, speed or fuel info.
Can I swap out the gauge panel from eBay anything specific to look out for? I like the look of an SS better than the base, are they compatible?
 

Ross

Goblin Guru
I have run a base and SS instrument panel, they both worked the same. Intermittent. So it didn't fix my issue, but it only cost me $25 at a auto recycle yard. I thought I would have to re-calibrate the speedometer from 160 mph to 120 mph, but no, they both correctly indicated the speed.
 

Jcas

Well-Known Member
Really need to re-check your grounds. Be absolutely sure no paint (or powder coat) is under your grounds. Scrape it off. The ground itself will cover the missing paint. Some things can operate with a marginal ground and others will not. A good ground is critical.
Yes I to had a short gremlin and it was powder coating on ground lug. Also my cluster is a bit touchy with the plug in the back had to work it over so that I had a bit more room between cluster and the top tube behind it because it caused funny thing with gauges and some times only read out would work and all guages would drop to 0. Also check that your plug is making connection to the cluster as I had a problem with that on a clutch switch. All tests found nothing but was not making contact to switch itself
 

CaptFrank2001

Well-Known Member
I'm sure I sound like someone overstating the "grounding" problem (lack of a good ground). And your use of Gremlins is a good way to put it. A poor ground can cause all types of issues, the worst being the intermittent ones. A poor ground can act as a resistor in some circuits and as a capacitor in others, or both. That can cause all kinds of problems. At your grounding points scrape off ALL that paint/powder-coat to bare metal & also clean the lugs you attach to the grounds.
 

Anks329

Well-Known Member
I took a break from trying to figure out the instrument panel and went for a drive. It’s going to get more difficult soon as the rainy cold season is getting started, but enjoy the weather while I still can! It’s still a little twitchy at ~60 mph, so I need to work on my alignment a little more. It also definitely needs a tune, I need to place the order for the wideband and HP Tuners in a couple of weeks.

But, it’s so much fun to drive and answer questions at the gas station :)

17618
 
Top