1989..Erratic idle & dead batttery=ECU or starter?????

[Jennie7951]

Okay so I just got an1989 bronco. 5.0 .. I drove it home from the sellers house just fine.. Then I went to the Waffle House and when I got done eating. I came out side and it was DEAD! .. I don't believe I left a light on... So I called a friend to come get me and take me to get a new battery... When I replaced the battery.. It idle high then died..it did this 3 times before it stayed running. I let the truck run for a 1/2 hr and then turned it off... When I restarted it, the starter sounds VERY loud.. Just didn't sound right at all.. .. Is my starter going or could it be a shot somewhere in the electrical.. what causes a dead battery, erratic idle and the starter noise to become loud...??

Any help troubleshooting would be great!!!!

~Jen

 

[rednecktrkdrvr]

it could be the starter has a dead short that is drainin the battery and if it is fuel injected the throttle positioning senser will cause the high idle i had the idle problem on my 94 and i changed out the senser and that fixed that problem

 

[miesk5]

yo!

Check for Codes;

Our pal Joe has a good DIY test;

SELF TEST - COMPREHENSIVE & Connector Location pics, Bronco & Ford

Source: by BroncoJoe19 (Joe) at broncozone.com

Do da Key On Engine Off (KOEO) test to get the Codes

Post codes here or look for some in my Broncolinks.com site under Electronic Engine Control (EEC) - EEC-IV; Overview, Self Test & Connector Location & pics; Diagnostic Trouble Code (DTC)

Look at the Links that say, DTCs 2 digits & some Possible Causes

TPS as Red wrote is a common problem; and low batty voltage can cause all sorts...

Check starter mounting bolts - & all cable/connections... look for corrosion there and at all Grounds from BATTY NEG to engine/frame/firewall/inner pass side fender, etc. Loof for

corrosion there as awell as between wire strands under connector...

Circuit pulls up to 500 amps depending on the starter, the engine load, and battery condition. Voltage measured at the starter during cranking should always be above 9.5VDC.

another starter noise prob could be that da Pinion does not retract - check condition; or have it tested free at NAPA etc.

With Key in ACCESSORY position & all accessories (radio, dome light, etc.) off, pull one fuse @ a time and look for arcing to narrow down any accessory w/a short