[silver2u]

the battery had been running low in the previous weeks and wasnt charging correctly. a local auto electrician did a very basic check and said the alternator was not charging the battery ( this confirmed my battery measurements of +/- 12 volt before crank, which then drops to 11.1 when engine starts i/o going up to 13.5 or 14 v)

i ended up replacing the alternator myself, took me a week to do it ( * RHD* car, removed battery tray and fuse box, then removed gearbox brace to lower rear engine mount).
but no resolution of my problem, the battery is still not rising to 13.5 or 14 volt when the engine starts.

i thought that when i re-connected the wiring on the new alternator, that the thin wire attaching to it felt rather flimsy and loose where it was attached at the other end (somewhere higher up on the engine near the injector rail) , and might be frayed or damaged at this other attachment point . but i checked this thin wire going to the alternator as extensively as i could for any signs of cracks, corrosion or wear, but cant see any problems by simple visual inspection.

i traced it from its alternator attachment point all the way back to where it joins up with the yellow starter motor cable (and another sensor wire) and then enters part of the wiring harness (near the CPS sensor bracket, behind the fuel injection rail). at that entry point these 3 wires enter a hard plastic heat shielding cover , and i stripped this back 2 or 3 inches to make sure no damage was present , but cant visually see any problems

looking at the WIS wiring diagram to the alternator connections (wiring harness / charging system ), once this thin wire enters the harness it travels to the large electrical connector on the firewall just below the windscreen, not sure what i can check there

any suggestions on what else might be causing my alternator not charging the battery problem ?
- the battery is almost 2 yrs old and has been checked by the manufacturer's rep at the retailer i bought it from. i also had a loan battery from them for 2 weeks and still had the same problem
- error symptoms developed gradually over 2 months, slowly worsening (battery gradually weakening)
- "battery error light" and "exclamation point warning light" are on at dash
- OBD2 error code is PO560 = " system voltage"

i dont have access to a tech2, would this give a more specific indication of the error source/location ?

 

[Mimmi]

Check fuse 27 in dash fuse box.

 

[Mariner]

Battery / Charging indicator Light ??

Does your 'alternator bulb' (battery shaped indicator) light up when the car is turned to ON but not started ? From WIS, I THINK that this lamp no longer is the source for the energizing voltage to power the alternator coils - but I am not certain. That used to be the case, and a bad bulb could cause an issue such as you are experiencing. Never the less, if this lamp does not light up when ignition is ON but the engine is not running, there is an issue.

My direct test would be to run a light test wire from the energizing (small) alternator lead out to a spot where you can clip on your volt ohm meter (VOM, multimeter) and measure to see whether you have voltage to that lead when you start the car. If not, trace the lead back as far as necessary. If you have voltage there, then re-run your test lead to the output terminal of the alternator and see if voltage at the alternator is ca. 14V. If you have energizing voltage and no output . . . alternator. If you have alternator output but not at the battery, then loose connectors or bad positive cable.

If your 'new' alternator is rebuilt, it is still possible it's got an issue. I've had even new OE parts which were faulty.

P.S. Double check all grounds

Good luck on tracing this. I'm sure it seems maddening now.

 

[CJPeterborough]

As above...


Where are you measuring the voltage?
At the battery or at the alternator itself?


The 9-5 is notorious for internally corroded +ve cable giving voltage drop.
Good idea to measure at the alternator and see if its output is good or not.

 

[hunterstein555]

Not helpful but I'm curious as to why you had to remove the battery tray and such when it's a LHD car?

 

[redaero-wagon-2000]

Does your 'alternator bulb' (battery shaped indicator) light up when the car is turned to ON but not started ? From WIS, I THINK that this lamp no longer is the source for the energizing voltage to power the alternator coils - but I am not certain. That used to be the case, and a bad bulb could cause an issue such as you are experiencing. Never the less, if this lamp does not light up when ignition is ON but the engine is not running, there is an issue.

My direct test would be to run a light test wire from the energizing (small) alternator lead out to a spot where you can clip on your volt ohm meter (VOM, multimeter) and measure to see whether you have voltage to that lead when you start the car. If not, trace the lead back as far as necessary. If you have voltage there, then re-run your test lead to the output terminal of the alternator and see if voltage at the alternator is ca. 14V. If you have energizing voltage and no output . . . alternator. If you have alternator output but not at the battery, then loose connectors or bad positive cable.

If your 'new' alternator is rebuilt, it is still possible it's got an issue. I've had even new OE parts which were faulty.

P.S. Double check all grounds

Good luck on tracing this. I'm sure it seems maddening now.

Very good advice. You have to know the voltages at the alternator and the battery.

I have seen 2 corroded battery cables [internally]. And many dead batteries and actually no dead alternators.

Check tols voltage points and load test te battery.

 

[silver2u]

CJPeterborough: the previous voltages i mentioned for engine off and on were measured at the battery contacts

fuse 27 in fuse box seems ok at initial check, i will replace it on my next testing to exclude it fully
the battery error light on the dash comes on as soon as i turn the ignition on, and stays on when the engine is started and running


ok, not sure i understood 100% how to correctly do the measurements from the alternator suggested (correct me if i am wrong), but knowing that the alternator grounds itself by direct physical contact on the bracket and car body, i presume both contact points i will now measure with my volt meter from the alternator will be +ve contacts on my volt meter ? i used my battery -ve terminal as the ground point for my volt meter (? correct), and then used the +ve of my volt meter to contact the each lead i had attached (one at a time) to the alternator contacts

the new measurements are:
- at starting new test : direct battery contacts w engine off = 12.49 V

now for the new direct alternator measurements:
- engine off and ignition off, big alternator nut contact point = 12.49 v
small alternator nut contact point = 0 v
- engine off and ignition on, big alternator nut contact point = 12.03 v
small alternator nut contact point = 0.77 v
- engine on and running, big alternator nut contact point = 11.79 v
small alternator nut contact point = 0.77 v

note: i did not disconnect the alternator wiring for this testing

the engine was only running for a few min, but when i switched it off again the battery voltage (engine off / ignition off) had slightly reduced to 12.3 v This would seem a very small drop, but from past experience it would gradually reduce further the longer i would leave the engine running (or restart it multiple times etc).

it is late evening here (and winter), so tomorrow i will do the same test again and add switching on high beam lights (and rev engine test etc) to see if that fluctuates or alters the direct alternator measurements

so to me these initial results would suggest:
- there is a small voltage (0.77 V) at the energizing (small) alternator lead when the ignition is on or the engine is running (is that voltage high enough ? seems very small)
- the test lead to the "output terminal of the alternator" (big connector i assume) shows a voltage (11.79) when the engine is running but it is not ca. 14V. so does this mean there is "no output" ? eg it is just reflecting the voltage from the battery connection lead i assume, so no "output" from the alternator providing a charging current of approx 14 v

the new alternator is from rockauto in the usa and is a refurbished bosh one (refurbished by bosh, has their bosh serial number and refurnished item sticker, so certified bench tested and functioning by them). i doubt it would be faulty, but this is possible.

i will take my original alternator to the local auto electrician and let him bench test it, but i probably wont know the results till monday

anything else i can try to identify the cause of the problem ? (the bearing on my old alternator feels good when i turn it, and cant see/smell any obvious electrical problems of a major malfunction type)

grrr, really hope the new alternator is not DOA, it would be a frustrating delay to send it back to the usa and wait for a replacement, i would also hate to send it back to them and then be told it is functioning fine when they test it

 

[redaero-wagon-2000]

How is the RED battery cable? It is not rare for them to corrode from the inside.

Often it will not show on the outside.

Are you 1000% sure it is OK???

Stop and check this out before you do any work. You may have to take in insulation back a bit. If you see ANY corrosion replace the cable.

It is not a rare occurrence on the 9-5

 

[silver2u]

the red battery cable i presume is the thick cable which attaches to the large alternator contact ?
- at the alternator contact end it feel solid and rigid, and no play or looseness when i move the big ring contact that goes onto the alternator

at the battery end i havnt noticed anything unusual when i disconnected and reconnected it multiple times in the last few weeks, i will peel back the insulation material near the big battery clamp and will check that

if it is that cable, can i test its conductivity in any way ? i just have a basic volt meter (with ohm and amps etc)

 

[Mariner]

Interpreting symptoms . . . .

Hi Silver2u -

These data suggest a bad alternator. No power at the alternator Large Nut (B+) lug rules out the large positive battery cable as the prime suspect (it doesn't tell you it's good, but it wouldn't cause your result).

The small exciter lead (D+) on the alternator is showing at least a switch in the voltage with the state of the ignition switch - which is as it should be. This means at least part (all ?) of what the in-dash circuit is supposed to do is happening. No power from the alternator B+ is not what should happen.

The D+ lead initially energizes the stator coils to create a magnetic field for the armature coils to pass through and create current. As it ramps up power, the alternator regulator feed more voltage to the D+ to increase the fields and thus the alternator output. The regulator will keep increasing the voltage until the output gets to about 14V, and then it will level off so the voltage doesn't run wild.

The drop in voltage at the B+ lug as you turn ignition on and then run the car follows from a bigger load on the battery, AND no power from the alternator. This fairly screams the alternator is bad, but I haven't been able to find the SAAB spec for the base level voltage on the D+ lead. I will have access to one of the two SAAB 9-5's I maintain this Sunday p.m. local time, and I will check that car then to see what it shows for D+ voltage.

Sorry I can't be more encouraging.

 

[Mariner]

Update - see this old post, and . . . .

Hi Silver 2u -

I found an old post (via Google search) about similar issue - LINK.

Seeing this, I would disconnect the D+ connector, carefully connect it to my extension lead, and wrap the joint with electrical tape. Then measure the voltage to the D+ lead with no attachment to the alternator: 1) with ignition OFF, 2) with ignition ON but not running. If you see about 12V then I think you could confidently blame the new alternator. A bad alternator regulator assembly might drain power off the D+ lead - this way you test separately. The post I linked infers that the D+ voltage should be about 12V or battery voltage.

 

[Mariner]

More information - from someone who knows SAABs

Here's a response I got from a seasoned SAAB mechanic on another board:


Hello,

The exciter wire should have 12v on it all the time. As a test to see if the alternator works run a small wire with a 10 amp or so fuse on it directly from the battery to D+. He should then get 14v or so at the big B+ contact at the alternator. I have seen a few times on early 9-5's were the wire for D+ was corroded in the large connector on the bulkhead. I am not sure without seeing the wiring diagram if the bulb failing in the MIU will cause the alternator to not charge like on old 900's. Does the warning lamp on the MIU light with the key on and the car not running?

Good Luck, Bernie


Hope this is helpful.

 

[silver2u]

Hi Mariner,

thank you for the detailed further information. i have been trying to think (and done some further searching online) how i could check for the 14v output from the alternator without having other leads connected to it that might distort the measurement process (for ex the starter motor connection)

i will also redo the previous measurements i did, but use a engine block earth point as a ground, instead of the connector at the battery clamp (and compare ignition off/ignition on in more detail)

one thought i had (but this might not be safe ?) is to disconnect the large electrical lead attached to the alternator B+ contact (which is also connected to the starter motor, and then onward to the battery)
- and to then directly attach my volt meter to that B+ output point (which should produce 14 v + when the engine is running with the serpentine belt driving it)
- but do this without anything else connected to that B+ terminal at the same time which might be distorting the measurement
- the earth of my volt meter i would contact on the engine block

i will also try and "jiggle" a few wires while my volt meter is attached and the engine is running, to see if anything triggers a change in voltages


redaero, thx for the tip, i will also check this connection further

 

[Mariner]

safety - yes

I agree about NOT disconnecting the B+ lead from the alternator, for two reasons. The alternator won't work properly in the car unless it can function under load (the battery and the rest), and safety concerns.

If I had leads to both B+ (power) and D+ (exciter) attached firmly & safely. I would have a helper apply battery power to the D+ as Bernie suggested with a 10A fuse in line. Measure the B+ at ON, Start, and Running. If the D+ at battery voltage 'fixes it' then your alternator is okay - but you'll be looking for where the D+ voltage is lost. If battery voltage to D+ doesn't fix it, then the alternator is your culprit.

 

[silver2u]

ok, it has taken a few days to get the items to do the testing, but it is not looking good for my rockauto Bosch unit ( Bosch AL0813X, eg re-manufactured by Bosch themselves)

Setup:
- power supplied to the D+ alternator terminal via a 10 A fused wire (directly from the battery +ve )
- am measuring voltages at B+ terminal of alternator (volt meter -ve lead is attached to a car earth point, not the battery)

Battery Voltage before testing (at posts): 12.71 V

B+ alternator measurement:
- ignition off = 12.4 V
- ignition on = 12.11 V
- engine started = 11.78 V
- engine running and lights on high beam= 11.65 V

but within a few min of leaving the engine running, the Volt reading continued to decline significantly, 10.4 , then 10.2, then 9.6 Volt. every 10 or 15 sec it was reducing further. when i then switched the engine off and tried to restart, it barely crancked over and would not start. after letting it rest for 10 or 15 min, the voltage reading had returned to 11.55 (ignition on) but it wouldnt start (weak cranck). from recent experience i would need to put the battery charger on it for 2 or 3 hrs, and it will start again.

oddly, with my previous alternator (the saab oem one i was having problems with), with a charged battery i could still go down the local shops and drive it back home. with this replacement alternator i barely get one start from it and do a few min testing before the voltages drop to 9.6 V (and i think the car would stall soon thereafter)

i will repeat the measurement again tomorrow, just to make sure i didnt make an error in my setup.

 

[Knig]

I realise I may be telling you how to suck eggs, but could it be possible you've still got a bad battery. i.e bad battery knackers alternator, change battery but still bad alt, replace original battery and fit new alt therefore keeping an unknown battery still in circuit.
(from a non-mechanic)

 

[Mariner]

Comments

Silver2u -

It's possible for a really bad battery to cause issues, but this battery seems to be rechargeable back to the 12.3-12.5V range and produce enough current to start the car. The fact that the car doesn't run as long now on the battery alone now points to the alternator being an extra load on the battery and/or the battery may be suffering from repeated deep discharge. A new battery might very well be in order, but none of this should stop a good alternator from generating its rated 13.5V to 14V once under rotation at speed. The alternator is simply contributing no voltage.

Did you have a chance to test the D+ lead voltage with the lead disconnected from the alternator and ignition switch ON ? This matters for two reasons: confirm that the alternator actually gets the Battery voltage (ca 12V) at D+ from the car's ECU, and one more data point against the alternator - in case the alternator is "sinking" what should be Battery voltage down to the < 1V you observed for D+ earlier.

If the D+ lead goes to Battery voltage when ignition is ON, then your ECU is providing the proper power - and a GOOD alternator should work fine. If D+ lead does NOT go to Battery voltage, then we don't know for certain whether the old alternator was truly bad.

I order from RockAuto, and they seem quite fair. All of their returns processing is on-line without access by telephone. I returned a brand new brake master cylinder to them which was bad out of the box - it leaked from the main shaft seal while bench bleeding. I enclosed a note clearly identifying the issue. They gave me a refund within about a week from the day I posted the part back. I think that the information from this thread should go a long way toward explaining the issue, especially that 12V applied to D+ did not result in any voltage from B+ while the alternator was turning.

 

[silver2u]

its getting more confusing
since sending my (most likely) defective alternator back to roackauto in the usa for a replacement is time consuming, i improvised

my initial alternator was not charging the battery and had gradually worsened over several months. this might just have been the voltage regulator or the alternator itself, or possibly another electrical fault. when the alternator was out of the car, on superficial assessment the bearings felt ok

the replacement alternator i received from rockauto was completely non functional after i installed it , and seemed to additionally drain the battery very rapidly (voltage going down rapidly over just a few minutes).

so i took the rockauto voltage regulator and placed it in my old saab alternator, and then reinstalled that alternator
- battery before starting engine: 12.54 V (at battery clamps)
- engine started: 14.30 V excellent, for the first time i am getting a sign my alternator is working again, i thought my problem was solved !
- engine still running few min, and lights high beam on : 14.10 V
- with engine off after 5 min running : 12.87 V first time the battery slightly charged after keeping the engine running
- do an OBD2 check, no error codes

so i thought my problem is solved , and do an oil change and replace the oil filter (warm engine), remove car stands and jack, put tools away etc...

then 1 hr later i try and start the car again , and now it behaves as if battery low (one weak crank then nothing), no start !
- battery reads 11.63 V
- after 30 min resting it reads 11.88 V , so slowly a slight sign of some recovery (good)
- obd2 error code PO560 again now ("low voltage")

i didnt leave any lights on iirc, but the obd2 was connected and "on", this really shouldnt have drained the battery (unless the unit is faulty and maybe creating a short circuit)

i'll charge the battery overnight and check in the morning how it behaves, but imho if there was no other electrical fault (like poor ground etc, or a short somewhere), it should have started with the battery @ 11.63 V (just a guess)

 

[Mariner]

If we had started with these results, I would have jumped on "need a new battery". After you charge the battery overnight, be sure to let it sit for several hours and remeasure the voltage. Depending on how the battery is failing, it may go to a "fully charge voltage", but can still produce little current before the voltage drops off as you are observing.

Here's an article on sulfonation, one form of battery failure - but it's not the only one. Running the battery very low or low charge for protracted time or in cold conditions are conducive to this kind of failure.

Perhaps borrow a known good battery again and see if it does the same before you put out the money for a new one (I feel the pain).

 

[silver2u]

success at last !

charged the battery overnight 6 hrs
- 13.34 V after charging this morning
note: this is better then the 12.54 V pre-start yesterday when i first tested the new voltage regulator on my old alternator. i dont think i had recharged the battery for a number of days before then, and when used previously i still had the rockauto alternator malfunctioning and rapidly draining the battery.
- 14.40 V at battery posts with engine running today, same good voltage as when i previously tested the new voltage regulator yesterday

drove the car straight to a car battery retailer , and they stress tested it on the car (putting an artificial high amp load on it). battery results were 660 CCA, which is slightly higher then its rated spec of 640 CCA (eg battery very healthy for a 2 yr old unit from a locally made mid range brand)

been a bit nervous driving and start/stopping the car the last few days, but all is back to normal and the alternator is functioning correctly at last

Mariner, and those providing useful input, thx for your help in trying to resolve this ;ol;

the summary of this protracted problem is
- the original alternator had a progressively weakening voltage regulator, and after a few months this completely stopped charging the battery
- the replacement alternator from rockauto was completely defective and functioned as a "sink" and major drain, confusing further diagnosis.
- the voltage regulator from the rockauto unit functions correctly, and matched with my old alternator gives me a functioning unit
- removing/installing an alternator on a RHD model is a MAJOR undertaking that takes a non-mechanic several days (if everything goes smoothly). it is also potentially dangerous as 2 of the 3 the engine mounts have to be disconnected. it is however not that complex, and with the right tools can be done
- an earlier forum poster with a RHD model 95 said he had replaced a voltage regulator several times without fully removing the alternator from its mounting bracket. from my recent experience i now agree this should indeed be possible and will try and do this when my new voltage regulator arrives from Eeuroparts. (i need to send my defective alternator back to rockauto for a replacement, and have to put back their voltage regulator i am currently using)

Mariner, thanks again for your help in trying to resolve this protracted issue !