nmyron3983
Junior Member
- Joined
- Aug 20, 2022
- Posts
- 16
- Reaction score
- 6
- Location
- Beavercreek, Ohio
- First Name
- Nathan
- Truck Year
- 1987
- Truck Model
- V10
- Engine Size
- 350
I hate to kick a long-dead horse, but here goes.
I have an 87 V10 350 4-speed. It runs, but for the duration of the time I've owned the truck, the SES light has never worked. The ALDL circuit to pins A/B works, I was able to jumper that to reset the IAC after I replaced it, I could hear the IAC motor clicking, the pintle seated fully, but no SES. There is never an SES at startup either. But the truck runs acceptably, albeit a bit rich and stinky from what I can tell (but the P.O. pulled the CATs, and I stripped the A.I.R. smog system, so maybe that's just "the way of things" now, as of yet not sure).
I followed the below guides provided by @chengny (BTW, where are these two pages from? I could not find them in the 87 FSM, or the 87 factory wiring diagrams?? I'd love to have a copy of this guide for my own diagnostics purposes). Firstly I stripped the dash apart and pulled the cluster, and checked every bulb. I did have some dead lights for cluster backlights, but the SES bulb itself was fine. The lights that were there were already dim, so I went ahead and stripped the cluster apart and put some nice bright white gloss paint in the cluster bucket and reassembled everything. So now my lights are nice and bright and clear, but still no SES.
So I went to the ECU harness. Just prior to the ECU, there is a 4 or 5 pin box connector that feeds BRN/WHITE as well as a few other circuits into the ECU. I popped that apart, and using a test light grounded BRN/WHITE, what should be Circuit 419 for the SES. I got a light on my test light with the ignition on, and polarity indicates it is a ground path. This tells me that indeed, voltage is making it from the cluster to C419's ground path. But the light on the cluster did not illuminate (I would think, since I'm grounding it's dedicated ground feed from the ECU, it should have). A caveat to this is I was not using a standard 12V test light, I was using the 'computer safe' variety that also uses green/red lights to indicate the polarity of the path you're tapping. I believe these only conduct millivoltages, not a full 12V.
Should I redo this test with the proper regular test light? Should I expect to see, with key on and C419 grounded, my test light illuminate and also the SES light on my dash light up? Pardon for a somewhat "dumb" question here. I've done a lot of work on my own cars over the years, but besides stereo installations I've never really had to deal with too many wiring gremlins, so I'm a bit new to this type of troubleshooting.
I have an 87 V10 350 4-speed. It runs, but for the duration of the time I've owned the truck, the SES light has never worked. The ALDL circuit to pins A/B works, I was able to jumper that to reset the IAC after I replaced it, I could hear the IAC motor clicking, the pintle seated fully, but no SES. There is never an SES at startup either. But the truck runs acceptably, albeit a bit rich and stinky from what I can tell (but the P.O. pulled the CATs, and I stripped the A.I.R. smog system, so maybe that's just "the way of things" now, as of yet not sure).
I followed the below guides provided by @chengny (BTW, where are these two pages from? I could not find them in the 87 FSM, or the 87 factory wiring diagrams?? I'd love to have a copy of this guide for my own diagnostics purposes). Firstly I stripped the dash apart and pulled the cluster, and checked every bulb. I did have some dead lights for cluster backlights, but the SES bulb itself was fine. The lights that were there were already dim, so I went ahead and stripped the cluster apart and put some nice bright white gloss paint in the cluster bucket and reassembled everything. So now my lights are nice and bright and clear, but still no SES.
So I went to the ECU harness. Just prior to the ECU, there is a 4 or 5 pin box connector that feeds BRN/WHITE as well as a few other circuits into the ECU. I popped that apart, and using a test light grounded BRN/WHITE, what should be Circuit 419 for the SES. I got a light on my test light with the ignition on, and polarity indicates it is a ground path. This tells me that indeed, voltage is making it from the cluster to C419's ground path. But the light on the cluster did not illuminate (I would think, since I'm grounding it's dedicated ground feed from the ECU, it should have). A caveat to this is I was not using a standard 12V test light, I was using the 'computer safe' variety that also uses green/red lights to indicate the polarity of the path you're tapping. I believe these only conduct millivoltages, not a full 12V.
Should I redo this test with the proper regular test light? Should I expect to see, with key on and C419 grounded, my test light illuminate and also the SES light on my dash light up? Pardon for a somewhat "dumb" question here. I've done a lot of work on my own cars over the years, but besides stereo installations I've never really had to deal with too many wiring gremlins, so I'm a bit new to this type of troubleshooting.
