Crank- No start -Electrical mystery?

PLACE ANY ISSUES RELATED TO YOUR VAN NOT STARTING OR STARTING HARD IN HERE.
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Topic author
67mgzx
I am merely driving my van
I am merely driving my van
Posts: 2
Joined: Sun Jul 16, 2017 3:37 pm

Crank- No start -Electrical mystery?

Post by 67mgzx »

This one has got me stumped so I'll try you guys, this looks like the best collection of Astro wisdom on the web.

2004 Cargo,2WD died on the driveway, pulled in one night running fine and no start the next morning. After all the usual diagnosing I'm left with this- No spark, No gas and 1.25 volts between ground and the pink wires for the coil, ICM and pin 19 of the ECM as well as the pink feeding into the fuse box. I've traced the wiring until I've isolated the following-

12v. to the key (Red wire), ability to crank means a strong 12v.
12v. from the key (pink wire) means ignition switch is good
low voltage on the firewall side of the big pink at the connector through the firewall behind the battery
9k ohms resistance between the pink firewall connector and ground (means a short to me)

I can't seem to follow the pink under the dash, I've bought AllData for this van but the wiring diagrams are pretty vague when it comes to the convenience center and such. I'm guessing that it is not a broken wire or stripped insulation since it failed just sitting still, I'm thinking some failure in a relay/component that allows for a short.

Any hints or thoughts before I start stripping all the wiring out from under the dash? That is so my favorite place to work... (I'm 5-11 and 230)

Thanks, Steve

Topic author
67mgzx
I am merely driving my van
I am merely driving my van
Posts: 2
Joined: Sun Jul 16, 2017 3:37 pm

Re: Crank- No start -Electrical mystery?

Post by 67mgzx »

An update for those of you playing along at home, I spent 4 hours on Monday chasing down the short and think I've found my problem.

From AllData I figured out that the pink from the ignition also fed into 3 fuses in the interior fuse box-fuse #4 (Gages), #10 (Air Bag), and #16 (Turn-B/U). I pulled each and checked the circuit, #4 is the winner- the gages circuit.

Back to AllData to learn that there are 3 things on that circuit- DRL Relay, Instrument Cluster and the BCM. After disconnecting and testing the circuit for each- the winner is the BCM. With the BCM disconnected I have normal voltage at the coil and ICM and the fuel pump is priming, the van won't run but I'm guessing it needs the BCM to run.

I've ordered a used BCM off ebay, I found one that is the same part number but is a slightly different serial number-it is from a 2004 Astro so we'll see if I can use it without reprogramming, mine is a base cargo so there is not much "Body Control" going on.

I'll update again with the final result in a few days.
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okie1
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Re: Crank- No start -Electrical mystery?

Post by okie1 »

Thank you for the update, let us know if that is the fix as it may help someone else. :supz:
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