Charging curcuit help - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Krosati · 07-09-2003, 07:51 PM

Hi,
New to the group after checking around a bit. I hope someone here can help.

I recently purchased an 88 GMC Suburban and am having difficulty getting the charging system working. I replaced the alternator that was in the truck with the same type and replaced the battery. It still does not charge.

After purchasing a 5 book set of 1988 manuals, I am even more confused than ever.
1. What model truck is a 2wd sub? R or C?
2. The engine is a GM replacement 350 TBI. Would the RPO code still be L05?
3. According to the auto parts store, I should have a SI type alternator but the harness has the same long oval plug used on the CS121, CS130, and CS144 alternators. Was 88 a design change year or what?

Ok, since I have the wiring diagrams in front of me, I scan the C/K pages. Alternator plug is the same, fusebox is different, Instrument panel connector is different.
I now scan the G (van) pages, the alternator is the same, fuse box is similar, and the IP connector is different.
Now I check the R/V section and the alt is different but the fuse box and IP connectors are exactly as mine.
Which one should I use?

I've owned GM vehicles all my life and I never thought they could confuse me like this Burb is doing.

*mike reeh* · 07-09-2003, 08:29 PM

yes a lot of stuff changed in '88.. the trucks were redesigned while the burb/crewcab/blazer trucks kept the same body style..

are you sure its not charging? maybe something is draining the battery. Whats the voltage with the engine running, and engine off? at a slightly raised idle you should have ~14volts

mike

Krosati · 07-09-2003, 08:37 PM

No drain on the system, battery is all that's running the truck. Volt guage shows less than 12 when running and drops as long as engine is running.
I checked voltage from BAT connection, only shows battery voltage. If I disconnect the battery, truck dies.
If I rev the engine, no change in voltage.

Krosati · 07-09-2003, 08:50 PM

The problem I have is that since the diagrams are of no help, I need to know how to wire up a CS130 alternator bypassing the harness. Just to get it going.

*mike reeh* · 07-09-2003, 10:05 PM

well im not sure whats up with all the different part numbers but it sounds like probably just amperage. Did you have the parts store test the alternator?

I do beleive that if you disconnect the wiring harness, there should be nothing stopping the alternator from putting out full voltage.

might sound a little too simple but I cant think of how anything in the electrical system would keep the alternator from putting out 14 volts. an internally regulated alternator that is spinning at 1000rpm should be charging no matter what.

What kind of battery are you running? Has the battery been FULLY discharged at all? I was having some funny stuff happen when I was running an optima battery... If it got fully discharged, and I jumped it and drove the truck, it would fry the alternator.. went thru 2 new beck/arnley alternators and 2 optima red-tops before I figured it out.

good luck

mike

iufan71 · 07-09-2003, 11:52 PM

My dad had an 84 Suburban,that had all sorts of charging problems,never could get it straightend out,and got tired of it eating batteires,and finally donated it for a tax write off.

Krosati · 07-10-2003, 03:38 PM

Yes I had the alternator tested.
Battery is brand new and fully charged.
First time they said it was fine, 2nd time they said it was bad (different parts house).
I took it back to the original store and warrantied a new one.
The problem I have is strange. The check engine light comes on when I turn on the key but it goes out once the truck is running. There is no other ALT light that I can find. The shop manual says to pull the clip with the key on, the check engine light should stay on but it doesn't.
The other thing is, there are two wires, pink/black and brown. With the ignotion off, the pink wire is grounded and the brown wire has nothing. With the key on, the pink has battery voltage and the brown still has nothing. If I ground the pink wire, I pop the guage fuse.

07-09-2003, 07:51 PM	#1
Krosati Registered User Join Date: Jul 2003 Location: Texas Posts: 49	Charging curcuit help Hi, New to the group after checking around a bit. I hope someone here can help. I recently purchased an 88 GMC Suburban and am having difficulty getting the charging system working. I replaced the alternator that was in the truck with the same type and replaced the battery. It still does not charge. After purchasing a 5 book set of 1988 manuals, I am even more confused than ever. 1. What model truck is a 2wd sub? R or C? 2. The engine is a GM replacement 350 TBI. Would the RPO code still be L05? 3. According to the auto parts store, I should have a SI type alternator but the harness has the same long oval plug used on the CS121, CS130, and CS144 alternators. Was 88 a design change year or what? Ok, since I have the wiring diagrams in front of me, I scan the C/K pages. Alternator plug is the same, fusebox is different, Instrument panel connector is different. I now scan the G (van) pages, the alternator is the same, fuse box is similar, and the IP connector is different. Now I check the R/V section and the alt is different but the fuse box and IP connectors are exactly as mine. Which one should I use? I've owned GM vehicles all my life and I never thought they could confuse me like this Burb is doing.

07-09-2003, 11:52 PM	#6
iufan71 Registered User Join Date: Apr 2003 Location: Indianapolis,IN Posts: 138	Charging problem My dad had an 84 Suburban,that had all sorts of charging problems,never could get it straightend out,and got tired of it eating batteires,and finally donated it for a tax write off.

07-09-2003, 08:29 PM	#2
mike reeh 5 day ban, learn to behave. Join Date: Nov 2002 Location: san diego, ca Posts: 684	yes a lot of stuff changed in '88.. the trucks were redesigned while the burb/crewcab/blazer trucks kept the same body style.. are you sure its not charging? maybe something is draining the battery. Whats the voltage with the engine running, and engine off? at a slightly raised idle you should have ~14volts mike

07-09-2003, 08:37 PM	#3
Krosati Registered User Join Date: Jul 2003 Location: Texas Posts: 49	No drain on the system, battery is all that's running the truck. Volt guage shows less than 12 when running and drops as long as engine is running. I checked voltage from BAT connection, only shows battery voltage. If I disconnect the battery, truck dies. If I rev the engine, no change in voltage.

07-09-2003, 08:50 PM	#4
Krosati Registered User Join Date: Jul 2003 Location: Texas Posts: 49	The problem I have is that since the diagrams are of no help, I need to know how to wire up a CS130 alternator bypassing the harness. Just to get it going.

07-09-2003, 10:05 PM	#5
mike reeh 5 day ban, learn to behave. Join Date: Nov 2002 Location: san diego, ca Posts: 684	well im not sure whats up with all the different part numbers but it sounds like probably just amperage. Did you have the parts store test the alternator? I do beleive that if you disconnect the wiring harness, there should be nothing stopping the alternator from putting out full voltage. might sound a little too simple but I cant think of how anything in the electrical system would keep the alternator from putting out 14 volts. an internally regulated alternator that is spinning at 1000rpm should be charging no matter what. What kind of battery are you running? Has the battery been FULLY discharged at all? I was having some funny stuff happen when I was running an optima battery... If it got fully discharged, and I jumped it and drove the truck, it would fry the alternator.. went thru 2 new beck/arnley alternators and 2 optima red-tops before I figured it out. good luck mike

07-10-2003, 03:38 PM	#7
Krosati Registered User Join Date: Jul 2003 Location: Texas Posts: 49	Yes I had the alternator tested. Battery is brand new and fully charged. First time they said it was fine, 2nd time they said it was bad (different parts house). I took it back to the original store and warrantied a new one. The problem I have is strange. The check engine light comes on when I turn on the key but it goes out once the truck is running. There is no other ALT light that I can find. The shop manual says to pull the clip with the key on, the check engine light should stay on but it doesn't. The other thing is, there are two wires, pink/black and brown. With the ignotion off, the pink wire is grounded and the brown wire has nothing. With the key on, the pink has battery voltage and the brown still has nothing. If I ground the pink wire, I pop the guage fuse.



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