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Volvo 740 electrical gremlin help

34 messages,  Last post on Jun 23, 2012 at 1:36 PM

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What is this discussion about? Volvo 740, Electrical, Wagon

Messages Page 1 of 4

#1 of 34 Volvo 740 electrical gremlin help by sandeman1

Jan 09, 2006 (5:48 pm)

Here's a strange one that maybe someone has seen before:
 
A 1988 740 GLE with 190K miles. The alternator tests good (charging the battery), and just put in a new battery.
 
Indications: Above 2000 rpm, the idiot lights on the dash come on just as if there was a alternator problem. Below 1000 rpm the lights come on very very dim. Between 1000 and 2000 rpms the lights stay off.
 
Any ideas???

#2 of 34 Re: Volvo 740 electrical gremlin help [sandeman1] by vicenac

Jan 27, 2006 (3:58 pm)

Replying to: sandeman1 (Jan 09, 2006 5:48 pm)
Maybe the brushes are worn out (too short) or there is some dirt on the belt.

#3 of 34 740 problem by fred43

Mar 02, 2006 (4:18 pm)

I have a 1991 740 volvo no turbo. I have spent over 3 thousand dollars on a problem no one can solve. I get a trouble code 123 Coolant temp. sensor signal. I have replaced the sensor 3 times. The car is running very rich causing many problems. I replaced the engine brain box and that did not help. Fred

#4 of 34 Code 154 by topcat01

Mar 03, 2006 (5:23 pm)

I have a 1990 740GLE Volvo with 143K on the odometer. Since 2003 I have changed the EGR valve once and, EGR Vacuum Control solenoid three times. My check engine light is on now and still displaying the same old code of 154. My mechanic is questioning if my EGR temp sensor is bad or the ECU. Please share any knowledge on correcting this problem before it drives me over the edge.
 
tc

#5 of 34 Re: Volvo 740 electrical gremlin help [sandeman1] by mhyde

Mar 05, 2006 (6:59 am)

Replying to: sandeman1 (Jan 09, 2006 5:48 pm)
I just went thru (am going thru) something similar. First my car just cut out while driving one day. The mechanic said it was the battery (I thought it was the alternator). He replaced the battery, and two days later the car died while driving it. This time he said it was the alternator and replaced that. Two weeks later the battery (dash light) light was on along with the brake light, parking brake light and window washer fluid light. This time the mechanic said it was the alternator belt and replaced that. Now, two days later, the fuel gauge will only read full or empty and does so randomly when the car is started.
Is it time to give up on this 1989 car?

#6 of 34 I dont own a 740 I have s80 by walworth

May 16, 2006 (7:22 pm)

I want to ask if any one knows how to fix a sunroof problem my sunroof will not close and my door locks will not lock is it all part of the same siystem dose any one know how to fix tis problem

#7 of 34 740 problem check engine by valade

May 21, 2006 (7:37 am)

Hi i have a 740 gl 1989,with only 147 000 km,anyways i cleaned out the motor with some product,i didnt spray it with water,and as soon as i started the car the check engine light came on,the light has been on for about 2 weeks and always stay's on,i also noticed that its taking up alot of gas. I also have an other problem,my right wheel in the front is sort of blocked,i can use the car,infact it goes well, but something is jammed in the brakes,and they are still good(70%),but it seems to skip,and i have no abs,when i turn on the right side,my wheels just spin for a while,its as if the car is forcing leading the back wheels to spin,anyways if anybody could give me some advice id really appreciate it alot,thx

#8 of 34 Re: Volvo 740 electrical gremlin help [mhyde] by 740_fan

Jan 11, 2007 (2:39 pm)

Replying to: mhyde (Mar 05, 2006 6:59 am)
I think it is definitely the high time to change your mechanic in the first place, because he did a number of stupid things in his efforts to solve the problem (and if you paid him for all this, arrgh...).
It is difficult to judge anything without seeing the car, but from your description it is clear that:
1. The car cut out because the battery was empty (which was not the reason to install a new battery immediately).
2. The car died while driving it after two days, with new battery - not knowing how exactly the car was used during these two days is very difficult to judge or assume anything, but the least mistake may be made if saying that the new battery also went empty > there possibly is a problem with the alternator (but maybe not (only) the alternator, or, better to say when alternator is not charging, this does not mean that it is not good, there are other part of installation which may produce problems causing a good alternator not to work properly)
3. Mechanic said it is the problem with the alternator and he replaced it > he should have said what exactly was the problem with the alternator, it is not so difficult to understand. You never replace an alternator if you are not sure that it must be replaced, and you must know why it needs to be replaced. So far we do not know why the alternator was replaced, and what is more important, was it properly replaced (although that should be the most simple thing to do for any mechanic).
4. Dashboard lights, conclusion that there is a problem with the alternator belt > if there really was a problem with the alternator belt, such a problem should never occur only two weeks after replacement of an alternator, because: you inspect the old belt and do not use it unless it is really good, and you know how to install it (tension-wise) properly, being it old or new, so that in two weeks no problem with it should occur.
5. I assume that now everything works except the fuel gauge > this is a common problem with 740 dashboards, and can be caused by worn instrument which tends not to move from 0, especially when a tank is pretty empty, so the force needed to move the needle not too much from zero is small anyway (usually it is put in working condition with a solid tap of your hand on the dashboard above it), sometimes - when you fill the tank completely and the needle of an instrument gets stuck on the maximum you sort out this problem in the same way as explain above. If it goes erratically or stays at different positions abnormally during normal use of the car (car in move, not only engine working), problem may be caused by the worn rheostat in petrol tank, which produces signal for the petrol gauge. problem may also be caused by poor/corroded contacts at number of places.
6. It would be good to know whether, when the problem with signal lamps on the dashboard was spotted, was also any other problem present at the same time (for example with outside lights, cabin light, radio, etc). This problem (dashboard lights only) may be caused by the poor contacts on the instrument panel or somewhere else (fuse box, for example)
7. Very simple check-up of the alternator: when the engine is on and idling (best results immediately after starting a cold engine, and better in winter than in summer, but in general at any time), turn on at the same time both the headlamps and the fan switch to maximum (! not the airco, only the fan) and it must be noticeable that the number of revolution of the engine drops - you should hear this and you should see this on the rpm meter, if there is one. When you turn off lights and fan, again simultaneously, the engine speed must increase a little bit. Why lights/fan, and why after starting - because then you are using approximately 120 Watts which must be compensated/produced by a good alternator, and in order to produce the electricity, the alternator produces strong magnetic field and increases the overall resistance that the crankshaft is having at that moment, which is always anyway the biggest immediately after starting the engine (cold oil), and greater in winter (even colder oil, everything more stiff/rotating parts of an engine more close together, etc). If the battery is very bad, then you will have this effect more noticeable - which can be seen, for example when somebody is providing jumpstart to a car with a dead battery - if a car with good battery has engine idling, connecting the jumpstart cables to a car with dead battery will produce slowing down the engine of the car used for jumpstart, this can also be a good way to damage your alternator, or engine may stall - that's why people always press the accelerator pedal when the other engine is started, because at this moment we have: a) dead battery taking the power from a good battery, which must be additionally charged by the alternator (which may not be designed for such load...) and b) we have additional big need for electricity i.e. power for the starter motor of the dead car -... here I will stop.
8. A wire which provides the incitement for the alternator tends to cause problems in certain situations as well - if it is a car with an alternator below the exhaust manifold, and if the alternator was improperly maintained, replaced, whatever, and this wire left too close to the exhaust manifold, it tends to loose its characteristics - and must be replaced although it may look usable - you suspect on this if the wire is too stiff, or if the isolation is desintegrating at certain parts of it.
9. Described test of the alternator should be done after we know that the belt is properly tensioned, i.e. if it is suspected that the alternator is not working properly, first check the belt, then the alternator / other parts of the electrical installation PRIOR to removing the alternator.
Don't give up, I drive a 1989 740 with 615.000 km on it and have had no special problems in four years that I own it
Regards from Den Haag, The Netherlands.

#9 of 34 Electrical problem? by hbass

Feb 05, 2007 (1:30 pm)

I drive an 88 740gle. When I was driving 3 weeks ago, it suddenly cut off, no radio, power locks, power steering, and lights on the dash flashed. I had it towed to a volvo mechanic who had it for 3 weeks, did some work (checked alternator brushes, replaced ignition switch), and said they were unable to get it to malfunction. (It malfunctioned 4 times for me on the way home). It has since stopped working, it turns over, but won't kick to start, and when I put the key in the ignition, multiple lights on the dash light up. But still no power locks, radio, or or other things electrical. When it malfunctioned after picking it up from the mechanic, it did the same as noted in the beginning of this note. Any ideas?

#10 of 34 Re: Volvo 740 electrical gremlin help [sandeman1] by kmeyer

Mar 05, 2007 (8:51 am)

Replying to: sandeman1 (Jan 09, 2006 5:48 pm)
Check to make sure the harmonic balancer is ok.
The rubber seal between the two halves can wear out.
 
The the result is that the belt driven devices can turn slower or at times stop turning while the engine is still running fine.
 
I checked this by putting a white line from the inside of the balancer to the outer edge, then ran the engine while turning the steering wheel. When I shut the engine off and checked, the lines were no longer aligned.
 
This caused my battery to drain and the dash "idiot" lights to come on at various times, the worst being at idle while turning the steering wheel.

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