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1991 2.8 V6- Ignition Switch wiring

PostPosted: Thu Apr 15, 2021 9:37 am
by staggerlee
According to the manual, I have an open between the grounding lead and the ignition switch, Does anyone now the wire color for the ignition switch ground? or where that ground attaches?
Thanks.

Re: 1991 2.8 V6- Ignition Switch wiring

PostPosted: Thu Apr 15, 2021 10:36 am
by Buster28
I can't find a schematic for a 91 2.8L but it seems unlikely there is a grounded terminal on the Ignition Switch.
The schematic is from a 00 Trooper and is typical of all other Isuzu Ignition Switch wiring I have seen.

What problem are you troubleshooting?

Re: 1991 2.8 V6- Ignition Switch wiring

PostPosted: Thu Apr 15, 2021 12:04 pm
by Shawn Anthony
there are no ground wires in the ignition switch.

you only have the fallowing.
B+ supply
Accessories on
IGN on or "run"
&
Start

Re: 1991 2.8 V6- Ignition Switch wiring

PostPosted: Thu Apr 15, 2021 9:00 pm
by staggerlee
Alternator is not charging battery/send power. When jumped, truck will idle, but a voltmeter on battery shows battery drains down till motor stops. Already replaced alternator due to broken B terminal (would just spin with nut). Troubleshooting in the manual: if charge light does not come on, place fused jumper between L terminal and ground, if still does not come on, locate open between grounding lead and ignition switch. So I'm trying to figure out how to locate that open. The manual has a wiring diagram, which shows L terminal to junction to ignition switch (among various others) but no reference to grounding lead. Thanks for the help.

Re: 1991 2.8 V6- Ignition Switch wiring

PostPosted: Thu Apr 15, 2021 9:55 pm
by Shawn Anthony
staggerlee wrote:Alternator is not charging battery/send power. When jumped, truck will idle, but a voltmeter on battery shows battery drains down till motor stops. Already replaced alternator due to broken B terminal (would just spin with nut). Troubleshooting in the manual: if charge light does not come on, place fused jumper between L terminal and ground, if still does not come on, locate open between grounding lead and ignition switch. So I'm trying to figure out how to locate that open. The manual has a wiring diagram, which shows L terminal to junction to ignition switch (among various others) but no reference to grounding lead. Thanks for the help.


The L terminal is connected to a series parallel circuit. With the common connection being the L terminal one leg of the parallel circuit is for the battery light on the dash. This light circuit is connected in series to a fuse under the hood. The other leg of the parallel circuit is connected in series to the voltage sensing resistor located behind the dash. Then is connected in series to a fuse under the hood.

Check the dropping resistor for proper resistance and continuity on either side of the resistor to the end of the circuit. This leg is the control circuit for the alternator.

Re: 1991 2.8 V6- Ignition Switch wiring

PostPosted: Sun Apr 18, 2021 11:46 am
by staggerlee
Thank you , shawn anthony, I as focused on the other side (from the B terminal) since that's where the ign switch is shown in the diagram. Turns out, the connector for the l terminal is bad, only available through rock auto apparently. That aside, I can get continuity to the first fuse, but not the second. So it's likely the resistor, I have yet to locate that resistor, which according to my diagram should be a 510 ohs in-line, with white green wire on one side and yellow black on the other. Looking online for the resistor, all I can locate is the blower motor resistor, to be clear, the resistor to which you refer is not the same resistor, correct?

Re: 1991 2.8 V6- Ignition Switch wiring

PostPosted: Sun Apr 18, 2021 1:21 pm
by Shawn Anthony
You should not have continuity thru a resistor. You will need to measure the resistance across the resistor.

Re: 1991 2.8 V6- Ignition Switch wiring

PostPosted: Sun Apr 18, 2021 6:51 pm
by staggerlee
I never found the resistor, but with the connector repaired to at least last until wednesday the alternator is working. Now on to tracking down why there are no lights on the dash or why my fuel and temp gauges aren't working.