Vehicle: '98 K2500 Suburban Diesel
Yesterday I noticed that the 'wait to start' indicator on the instrument cluster (IC) wasn't coming on when the key is cycled. At first I thought it was a glow plug relay issue, but after some investigating, I noticed that several other indicators, notably the DRL, Battery, Water in Fuel, STS, and SES lights were also not coming on when the key was cycled.
I have swapped all my cluster bulbs to LEDs so I thought maybe several happened to go out. Upon pulling the cluster and testing though, I found that all bulbs worked fine when probed individually, as well as when power was applied to the PCB and cluster ground (so no bad traces). I even swapped bulbs and found that the same ones still weren't lighting when plugged back in to the dash. As an extra precaution I tested all fuses with no issues.
I next pulled up the IC pinouts diagram from this post and tested the dash pins which matched the non-working bulbs (1, 17, 18, 19, 20, 21, 23). On each pin I found that I had no power on ignition cycle, so I'm guessing the issue isn't with the cluster.
I'm looking at the service manual but am having a hard time reading the B/W diagrams, or finding some kind of test. All other indicators and gauges work fine--it's basically everything in the top-left corner of the IC.
Does anybody have access to some color-coded diagrams that are better than what's in the service manual? It's dang near impossible to look back there for chaffed wires so I'm trying to figure out if there's a commonality among these wires (e.g., common ground) that I can look at before resorting to more drastic actions.
Thanks
Yesterday I noticed that the 'wait to start' indicator on the instrument cluster (IC) wasn't coming on when the key is cycled. At first I thought it was a glow plug relay issue, but after some investigating, I noticed that several other indicators, notably the DRL, Battery, Water in Fuel, STS, and SES lights were also not coming on when the key was cycled.
I have swapped all my cluster bulbs to LEDs so I thought maybe several happened to go out. Upon pulling the cluster and testing though, I found that all bulbs worked fine when probed individually, as well as when power was applied to the PCB and cluster ground (so no bad traces). I even swapped bulbs and found that the same ones still weren't lighting when plugged back in to the dash. As an extra precaution I tested all fuses with no issues.
I next pulled up the IC pinouts diagram from this post and tested the dash pins which matched the non-working bulbs (1, 17, 18, 19, 20, 21, 23). On each pin I found that I had no power on ignition cycle, so I'm guessing the issue isn't with the cluster.
I'm looking at the service manual but am having a hard time reading the B/W diagrams, or finding some kind of test. All other indicators and gauges work fine--it's basically everything in the top-left corner of the IC.
Does anybody have access to some color-coded diagrams that are better than what's in the service manual? It's dang near impossible to look back there for chaffed wires so I'm trying to figure out if there's a commonality among these wires (e.g., common ground) that I can look at before resorting to more drastic actions.
Thanks