1995 Bonneville - Charging system failure - Not alternator!
#1
![Default](https://www.gmforum.com/images/icons/icon1.gif)
Hi, I'm new to the board - I'm hoping someone can give me some ideas on lots of electrical problems I'm having...
Car will not charge - voltmeter in dash reads 12V or lower. Over the last couple of months, it used to charge, then the voltage would go down, then slowly back up to 14. Over time the problem got worse, and now it spends way more time at 12V or lower than it does at 14. Sometimes it goes down to 13 or so too. My batt couldn't handle it the other day and I had to get towed.
Also whenever the voltage is at 12v, the car has no power. It takes forever to get going from a stop, if I floor it it only goes to about 2k rpm and the car takes it'* time gaining speed (not good when you need to turn into traffic).
Also when the voltag is at 12V, occasionally on start the engine will rev up to 2k rpm and stay there. If I push the gas a bit it will rev higher (3k) and stay there even when I take my foot off. If I put it in drive, the revs go down, but N or P and it goes back up...
Also sometimes I get a fast clicking from the Fuel pump relay and a relay under hood (closest to driver - what does this one control?) This happens when I put key to ON position. Car will not start while relays clicking.
Also when I put the key to ON position, sometimes the cooling fans turn on even though the engine is cold and the temp meter says they should be off. Sometimes when the voltage is 12V, the fans won't come on when they should - doh!
Anyways - the car is not reliable when the voltage is at 12V and I need to get the charging system running again...
I recently:
Tested alternator at autozone - PASS.
Tried new alternator anyways - same problem
Put old one back in - same problem.
new fuel pump because old one was whining a lot - same problem
new plugs/ wires / TPS
I checked every fuse in the car (all 3 panels) all are good.
I took apart the fuse/relay center and cleaned it up, made sure all connections good.
Charged battery
wiggled every wire I could find, trying to find trouble spot - only found unreproducable ghosts
Removed all fuses that I could and keep car still running - still have same problem...
Took computer case apart and looked at everything - looks OK, no burnt up spots, etc.
I'll try anything at this point - please help!
Thanks.
Car will not charge - voltmeter in dash reads 12V or lower. Over the last couple of months, it used to charge, then the voltage would go down, then slowly back up to 14. Over time the problem got worse, and now it spends way more time at 12V or lower than it does at 14. Sometimes it goes down to 13 or so too. My batt couldn't handle it the other day and I had to get towed.
Also whenever the voltage is at 12v, the car has no power. It takes forever to get going from a stop, if I floor it it only goes to about 2k rpm and the car takes it'* time gaining speed (not good when you need to turn into traffic).
Also when the voltag is at 12V, occasionally on start the engine will rev up to 2k rpm and stay there. If I push the gas a bit it will rev higher (3k) and stay there even when I take my foot off. If I put it in drive, the revs go down, but N or P and it goes back up...
Also sometimes I get a fast clicking from the Fuel pump relay and a relay under hood (closest to driver - what does this one control?) This happens when I put key to ON position. Car will not start while relays clicking.
Also when I put the key to ON position, sometimes the cooling fans turn on even though the engine is cold and the temp meter says they should be off. Sometimes when the voltage is 12V, the fans won't come on when they should - doh!
Anyways - the car is not reliable when the voltage is at 12V and I need to get the charging system running again...
I recently:
Tested alternator at autozone - PASS.
Tried new alternator anyways - same problem
Put old one back in - same problem.
new fuel pump because old one was whining a lot - same problem
new plugs/ wires / TPS
I checked every fuse in the car (all 3 panels) all are good.
I took apart the fuse/relay center and cleaned it up, made sure all connections good.
Charged battery
wiggled every wire I could find, trying to find trouble spot - only found unreproducable ghosts
Removed all fuses that I could and keep car still running - still have same problem...
Took computer case apart and looked at everything - looks OK, no burnt up spots, etc.
I'll try anything at this point - please help!
Thanks.
#2
Senior Member
Certified GM nut
Join Date: Sep 2005
Location: Home Sweet Home in New York
Posts: 2,009
Likes: 0
Received 0 Likes
on
0 Posts
![Mortehl is on a distinguished road](https://www.gmforum.com/images/reputation/reputation_pos.gif)
![Default](https://www.gmforum.com/images/icons/icon1.gif)
Get someone else'* battery and plug it in.
I've seen situations like this where the car electrical system is alright, and there'* dead cells in the battery that cause the car to act like the alternator is fried.
I've seen situations like this where the car electrical system is alright, and there'* dead cells in the battery that cause the car to act like the alternator is fried.
#4
DINOSAURUS BOOSTUS
![](/images/badges/Gearhead.png)
Expert Gearhead
![Default](https://www.gmforum.com/images/icons/icon1.gif)
When you cleaned the relay center. Did you pull and clean both battery cables at all ends to ensure good connection everywhere? This would be a good next step. They are known to cause issues like this.
#6
DINOSAURUS BOOSTUS
![](/images/badges/Gearhead.png)
Expert Gearhead
![Default](https://www.gmforum.com/images/icons/icon1.gif)
Originally Posted by mrk874
Car'* in the shop now, and they've spent some time on it and haven't found the issue yet.
#7
![Default](https://www.gmforum.com/images/icons/icon1.gif)
The shop replaced the computer with a brand new one. They tried a couple of junkyard comps, but they didn't work.
Fixed unspecified broken wires. The only wires I noticed that were repaired is the single red wire comming from the alternator. I checked this wire out before and it seemed fine, but maybe it had problems.
Sent alternator out for rebuild. Not sure it was needed, since alt was tested at Autozone and passed all tests. But at least I won't expect it to fail soon.
Now when the car starts, the voltmeter goes immediatly to 14+ and stays there. All the gremlins seem to be gone.
Considering all the diagnosing I did, I think the only 'real' problem was the computer, and the rest was diagnosing / standard procedure for debugging this sort of problem. I think that supports a lot of other threads that state that the computer in older Bonnevilles is awful.
Fixed unspecified broken wires. The only wires I noticed that were repaired is the single red wire comming from the alternator. I checked this wire out before and it seemed fine, but maybe it had problems.
Sent alternator out for rebuild. Not sure it was needed, since alt was tested at Autozone and passed all tests. But at least I won't expect it to fail soon.
Now when the car starts, the voltmeter goes immediatly to 14+ and stays there. All the gremlins seem to be gone.
Considering all the diagnosing I did, I think the only 'real' problem was the computer, and the rest was diagnosing / standard procedure for debugging this sort of problem. I think that supports a lot of other threads that state that the computer in older Bonnevilles is awful.
#8
DINOSAURUS BOOSTUS
![](/images/badges/Gearhead.png)
Expert Gearhead
![Default](https://www.gmforum.com/images/icons/icon1.gif)
Interesting. Thanks for sharing.
One thing I know is I went looking for a ECM for my 95 and it'* a tough find at any place that has a decent price. 95 was a troublesome year.
One thing I know is I went looking for a ECM for my 95 and it'* a tough find at any place that has a decent price. 95 was a troublesome year.
#9
![Default](https://www.gmforum.com/images/icons/icon1.gif)
BTW, Thanks for the help.
I also searched for PCM modules while I was debugging the problem. Here'* what I found:
Junkyard had a used one for $60, no gaurantees.
Autozone sells the 'cardone' brand of remanufactured PCM for about $130.
The shop said they put in a brand new one and chared $210 for it. I haven't looked at it.
Now I wish I had just sprung for the AZ one and saved some cash.
I also searched for PCM modules while I was debugging the problem. Here'* what I found:
Junkyard had a used one for $60, no gaurantees.
Autozone sells the 'cardone' brand of remanufactured PCM for about $130.
The shop said they put in a brand new one and chared $210 for it. I haven't looked at it.
Now I wish I had just sprung for the AZ one and saved some cash.
Thread
Thread Starter
Forum
Replies
Last Post
mattwz
Everything Electrical & Electronic
4
07-20-2007 05:08 PM
cthamer
Everything Electrical & Electronic
5
08-11-2006 07:07 PM
SSEimatt93
General GM Chat
6
10-31-2003 12:21 AM