740 GLE Electrical Questions

petershen1984 · Post by **petershen1984** » 27 Dec 2004, 06:26

Hey y'all,

I had a very disappointing trip to the mechanic a few days earlier. I told him my battery needs replacing, and he promptly tests the battery condition with this voltimeter thingy and claims my battery's fine, though I know for a fact that it's a) 3 years old, b) been discharged a few times and c) doesn't recharge well anymore.

I was like, duh, of course the battery seems fine, I drove the car to the shop after all!

He then sold me this starter interrupter relay device. Now, he claims this increases current flow to the starter motor or something. Is there really a virtue in installing this device?

Today, 300 kms later, I found myself stranded on the road side because the battery was discharged even whilest the engine was running. Erratic symptoms included, my CD player resetting itself due to lack of voltage; my two-pitched horn sounding "muffled." Even my instrument and headlights went dim, and I noticed wacky readings with the speedo and tach while standing (the engine was idling while the tach was drifting upwards to 2000 rpm). I could only get it started by jumping cables.

Anyway... my main question was about the starter interrupter device. What's its function in context with automobile ignition systems?

You can be sure, I'm going to an Auto Depot for a new battery tomorrow and staying away from my mechanic at least until the next oil change.

Any recommendations as to what battery specs I should get for my Volvo 740? I currently have a 12V 60 Ah battery, and I'm looking for a little more capacity and preferably maintenance-free. Any input would be appreciated. Thanks!

Volvord · Post by **Volvord** » 27 Dec 2004, 11:09

Season's Geetings Peter

First all I can say is definitly find a new mechanic. I have been a mechanic for over 20 years and has never heard of a "starter interrupter relay device". There is no device which sends additional power to the starter. Second the battery may be OK, your battery will only be as good as the entire charging system, you may have weak alternator output, poor ground or power connections, fauilt regulator, or a bad battery. The important thing is that the entire charging system should be checked and the appropriate repairs made. I have definitly delt with my share of customers who have driven in and insisted on having their battery replaced only to have them return the next day with a dead car because of a faulty alternator or other component that was draining the battery.

As for battery recommondations I aways imstall the largest power rating that will fit the location. I am not sure if your area uses similar specification but I use batteries with a minimum of 750 cold cranking Amps here is some info on battery ratings http://www.jci.com/bg/BatteryBasics/bb_ ... attery.htm

petershen1984 · Post by **petershen1984** » 27 Dec 2004, 22:54

My alternator belt is as tight as it gets, and I still get the screechy sound sometimes. I've read that the whole alternator might as well be replaced. Thus far, I haven't gotten any charge faults so I can only conclude it's a battery. I fear the scenario you described where your customer's new battery was drained within days!

I would dread it if my alternator starts to go, or electrical grounds. It's a big job.

Another day, I started my car and only the oil/battery lights went out and the idiot "BRAKE, PARK BRAKE, and bulb failure" stayed on for a few more seconds. That same day was when I experienced my first ignition fault, where I'd turn off the car and have no crank right away. I let it sit, and it came back...

Today I'm not visiting Volvo, so I can only pray that my new battery will last.

Volvord · Post by **Volvord** » 27 Dec 2004, 23:23

Alternator problems are not detectable without propper test equipement. A faulty diode will still show a charge on the dash gauge but will reduce the alternator output by about 50% and often result in a short that drains a battery quickly.

A faulty regulator can also cause reduced output and insuficiant charging of the battery.

Your squeeling belt can be caused by factors other than being loose. Serpentine belt grooves often collect sand and small rocks whick create a very slippery surface that will slip. As "V" belts wear they loose contact with the pulleys and slip. Belt replacement may be the only solution.

As mentioned earlier a competent mechanic with the correct tools, equipemt, and diagnosis can save a lot of time and agrivation.

petershen1984 · Post by **petershen1984** » 31 Jan 2005, 19:57

Bingo, Regulator - Thanks Volvord

Volvord · Post by **Volvord** » 05 Feb 2005, 08:24

Glad to help

petershen1984 · Post by **petershen1984** » 17 Apr 2005, 09:38

Hi Volvord, I have a question for ya on this topic again. I've fixed all the electrical problems mentioned in this board but I was just curious about one thing -

suppose the battery is almost depleted of charge (less than 12 volts), and has only enough juice to operate your lights and power locks, but not the starter. if you turn the key to cranking position, will the car try to start anyway (send below-par power to the starter), or will it behave like your car is not in Park or Neutral? (idiot lights still illuminated from ACC position, but no starter response) - this happened to me a few times when the old battery died on me. Idiot lights stay on, but radio power is interrupted in position III..

LaRy · Post by **LaRy** » 17 Apr 2005, 13:14

I had a squeeling sound every morning with my 740, it was squeeling for one mile. I changed all the belts, but had still exactly the same sound. I decided to take the alternator apart and relubricate the two roller bearings. The grease was really dry, so probably the balls in the bearings were sliding instead of rotating as long as the grease was cold. I used some compressed air to blow out as much dry grease as possible. I kept the bearing on the shaft just opening the dust covers. With new grease, it is working silent again.

kayakjunkie · Post by **kayakjunkie** » 10 May 2005, 15:58

Hi,

Just a note on the relay !

It is a fix for some auto (and some 5 speed) tranny and some cars (I know my old Volkswagen jetta had this particular issue).

It's called a load reduction relay and the instructions are included in Bosh's new starter boxes.

What it does it what your mechanic says it does: Boosts the electrical signal that is lost or reduced (which may be so for many reasons).

I don't know if it was expensive, but it should not have cost you more than 50$, and, might have been a decent fix.

I believe that Boosh also documented this fix in one of their forums, but I cant seem to find it.

Anyhow, just letting you know that your mechanic was not wrong, but I found very few mechanics who knew about this fix !

Cheers

JF

petershen1984 · Post by **petershen1984** » 11 Jul 2005, 09:24

LaRy wrote:I had a squeeling sound every morning with my 740, it was squeeling for one mile. I changed all the belts, but had still exactly the same sound. I decided to take the alternator apart and relubricate the two roller bearings. The grease was really dry, so probably the balls in the bearings were sliding instead of rotating as long as the grease was cold. I used some compressed air to blow out as much dry grease as possible. I kept the bearing on the shaft just opening the dust covers. With new grease, it is working silent again.

My issue was with this bent L-shaped mount. I didn't have to get new ones, as the guys who worked on my car were nice enough to weld the metal together again. While I was at it, I asked for four new belts and "killed the mocking bird."