91 sidekick electrical problem

[brandi]

park brake light comes on very dim & and lost of power. Turn heater or lights on engine shuts off. Will not start, have to push start to get it running again can not jump start. Disconnect plug under dash and rev engine everthing returns to normal everthing works fine for a short period of time then happens again. No set time. Would love some help with this. I am new to this forum

[jtgh]

define jump start?
black jumper from frame to frame and Plus red to red and it wont crank ?
start and crank are 2 diff.things.
if it wont crank ,when PROPERLY jumped , then the RED battery cable is bad,or bad starter or bad start line to the starter from ignition switch.

1, what is battery voltage now. no running.

what car is this, 91 What? 1.6L 8V, Side kicks with what tranny , is it 4wd.

first off your battery is dead, that is why any extra load kills the engine.
second the Alternator is bad ,because , its job is to pick up any slack the battery cant handle . like the head lights.

1: remove your battery ,and put in any charged 12vdc battery you can find.
do not close hood as foreign battery can short against hood if too tall << real .

does car start now?


2: take voltage readings of battery resting (not running)
and then take it running.

12.65vdc (68degF) at rest = charged. 12.5 is ok too.
14.7vdc running if Alternator is alive.

keep in mind batteries can short out inside and can really mess up the other car
that is trying to jump you.
always swap a battery first on all EFI cars. If you are not rich .

blowing up expensive electronics is easy.


tell me what you are driving.

[brandi]

91 sidekick 1600cc 4x4 with a manual trans. Yes, the battery has proper voltage and have checked all battery leads. altinator seems to work fine. by jump start i ment using another vehical fo try to jump my sidekick.
there appears to be a relay under the dash that stars clicking when this happens. when i unplug the relay and rev the motor up the parking brake light turns off, i then plug the relay back in and everything works fine for a little while.

[jtgh]

lets clear up the symptoms.
will not crank start. ( does starter motor crank robustly , grind,rind,rind ,ggggggrrrr?)
will not jumper cable start. ( same question?)
push start ok. ( EFI is ok and fuel and spark).

2 possibles.?
1, bad power to ECM.
( caused: bad MAIN relay below ecu)
( fuse panel corroded underneath, right front fender , engine bay)
( fuel pump shorting and overloaded ECU)


2: bad ecu. (very common on 91" !, just needs new CAPS)

(above assuming battery stays good 12.5v .

not sure what relay (wire colors?)
i will send full schematic to you.
see pm.

parking brake light works off 4 things, RWAL, handbrake, fluid level and brake pressure diff valve error) for now ignore it, as the RWAL puter is also losing power.



the only way to trouble shoot it :
my guess is there is a loss of power , with any load applied to the main dash power wiring. Head lights, etc.
this in turn limits power to the starter solinoid.

so measure here with HL on.
file:***D:/0_Our_Cars/Tracker/0_hosting/ECU/P&G.jpg

b1 , b7,b9, b16, must be 12vdc with head lights and fan are on just before and after cranking, if it is real cold the voltage can drop as low as 10v. (min)

then the critical grounds, at the thermostat housing and distributor must not be bad.

full set of schemos. next.

[brandi]

so after forever trying to figure this out it turn out to be a bad altinator. the altinator ended up having a burned out diode.
thanks for all your help and sorry it to so long to get back

[jtgh]

shorted alts. are hard to find.

your critical sysmptom was excessive battery drain.
my drain page covers the alternator drain last.

glad to see it is running again.

cheers. and merry Christimas

[jtgh]

it was a drain. see post #5