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did a cummins swap now no headlight/interior lights or radio

J

jaybuller

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Natchez, ms
Hello i am just finishing up my 4bt cummins conversion into my 89 k5. i cant seem to figure out why i have no headlights, interior lights,dash lights,radio or horn? the radio makes a static noise but that is it? also all my gauges work(no backlights though) and all my turn signals too. im at a loss i checked all the fuses in the fuse block under the dash but i dont know where else to look? all my grounds seem to be good and i have good battery power and the alt charges fine. Any of you have this problem before? is there a main fuseable link somewhrer or somthing? thnk you for any help!
Jay BUller
 
You screwed up wiring somewhere, and on motor where you have to hook up the solenoid for the injection pump, the alternator and starter. Maybe also sending units if you have electric gauges.

I'm thinking you probably did the swap with the battery still hooked up. The alternator charge wire may have hit the chassis at sometime and you burned up the fuseable link at the junction block.
 
well deffinatley did not do the swap with the battery hooked up lol, heck i removed the whole front clip to do the swap! i do agree though something is missing here.... i just cant figure out what circut powers those sytems that are not working... to many frakin wires!!!!
 
sounds like the power wire coming from your starter solenoid to the cab. Your starter should have a large wire to the battery and two to three smaller wires going to the solenoid. There is a medium wire that should connect to the same terminal as the battery wire. Could be the fusible link on the same wire. Also check the small block on the firewall near the top just to the driver side where the power wires converge.



1978 Blazer, Bonanza Edition. 4BT, NV4500, NP205, 14bff w/detroit w/disc, d60, 4.56, Light Armored Vehicle tires 11x16 Mich
 
thanks crawlink5 ,
ok so there should be another wire conected to the 12v from the starter? any idea what color the wire is that needs to have 12v to it for that circut? that sounds like it is going to be my problem. Thankyou very much. i dont think i fried anything cause never any sparks or bad things when i conected my battery for the first time after the swap
 
I looked at my cummins starter.

On the terminal where the battery cable is connected there are also two med wires red and tan. Should have the big hole connectors.

One med wire going to the solenoid from the key that is red. small hole connector.

These are factory wires on a 1978 Blazer. They were not cut or spliced. May want to dig up a wiring diagram if your wires are not factory or different from a 78
 
crawlink5 said:
I looked at my cummins starter.

On the terminal where the battery cable is connected there are also two med wires red and tan. Should have the big hole connectors.

One med wire going to the solenoid from the key that is red. small hole connector.

These are factory wires on a 1978 Blazer. They were not cut or spliced. May want to dig up a wiring diagram if your wires are not factory or different from a 78
Click to expand...
That color code don't make sense. Are you sure the wires aren't faded?
 
Thank you yall, that did the trick they work now! it was a thick power supply wire that i had cut when i was trimming the uneeded wires during the conversion. I didnt know what it was for so i just cut it off!!!! i got it wired back up now i just wire it to the junction box on the firewall. They work like a charm! When i get a chance ill through up some pictures of the swap, it turned out nice.
 
JDNobodi said:
That color code don't make sense. Are you sure the wires aren't faded?
Click to expand...

I am absolutely sure they are faded - and it was dark:30 with a small flashlight. What are the real colors? Could be orange and brown? Pink and brown?

But it looks like he got it. Its nice having an older simpler wiring setup with no ecm to muddy the water.

I enjoy my 4bt - just wish I had a 4L80E with a controller behind it instead of the NV4500.

EDIT: I see what you mean about the color codes not matching. But mine has worked flawlessly for about 6 years now so I think I'll just leave it as is.

The two wires coming off the bat terminal down there on the starter go to the junction block and the big red wire on the alt. The wiring diagram doesn't show this exactly but in a roundabout way.
 
The one going to the starter solenoid should be purple. I forget what color it fades to, but every diagram I see for blazers, it is purple.
 
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