1990 strange electrical problem

with the hood open: after replacing a radiator and reconnecting the cooling fan: i can start the van but if i turn on the headlights, the engine dies and will not restart. if i close the hood, the engine will restart.

in addition, the cooling fan will not come on at all.

Any help with this weirdness will be appreciated.

I understand this condition is new starting with radiator replacement. So I would check and recheck all those plugs and relays for mixed connections. CLosing the hood does a few things: some impact vibration....turning off the engine compartment light, and possibly, establishing some ground connection with hood lock pin, release cable....obviously no common pattern here. I'll like to know when you find out.

In addition to plus and relays, check for bent, pinched, frayed, or shorted wires as well. The vibration of shutting the hood may be just enough to seperate (or make) a connection.

Adding to what LMP mentioned about connectiors... My sister had mid-80s Cutlass Calias. If you turned the parking lights on, then shut off the ignition, it would continue to run until you shut off the lights. It baffled everyone that looked at it. Eventually, just through chance, it was discovered that there was a wiring harness on the firewall that was incorrectly hooked up. Both the male and female connectors were there, and positioned right to make it appear that they were to be connected, but they were not suppose to be. Unplugging that, the car operated as it should.

Weird problems like yours mkrug45 are always an adventure trying to figure out. Usually it ends up being something obsecure that if you had tried to engineer it that way, you never would have been able to have been.

loosen the bolts that hold the relay center down ,and check the underside for corrosion,