-
|
|
|
I have done this and can say positively without question your alternator WILL NOT CHARGE because the field circuit uses the idiot light bulb in the instument cluster to complete the circuit. NO HARM is done but the alternator is basically shut off and you'll have a dead or low battery before too long. I did not get far because I had headlights on at that time and they got rather orange so I scooted home right away. Probably an hour in daytime and half hour after dark...not too good. Battery age and condition unknown so it could be lousy.
LOOK NO FARTHER, the above info is GUARANTEED! haaaa.
p.s. you COULD look into simply jumping a bulb in the circuit with some alligator clips but need to check a schematic to see what wire, to where.. could be done though.
NEWYANKEE
--
Genesis 7:11
|
|
-
|
|
|
Why would you want to drive without the cluster?
|
|
-
posted by
someone claiming to be BWiley
on
Thu Jul 29 04:10 CST 2010 [ RELATED]
|
|
I'm having the cluster worked on, and the shop is three hours away. Even with a day in transit each way, and a day or two to fix it, it puts we without a car for the better part of the work week.
|
|
-
|
|
That "exciter" circuit from the panel to the D+ terminal just "kick-starts" the charging. Once the alternator is up and running, that circuit is not active until next time.
Theoretically (I'm not advising this) with the motor running, I believe the B+ terminal (battery +12V) could be momentarily applied to the D+ terminal to "activate" the charging circuit. The alternator would then generate voltage like it always does.
Of course that would still leave you with no instruments or warning lights.
For two 3 hour drives? Not me.
What kind of cluster work is the motivator here?
--
Bruce Young, '93 940-NA (current), 240s (one V8), 140s, 122s, since '63.
|
|
-
|
|
|
Hey Bruce, thanks for taking the time to explaining that to me. So the long story of it is this:
I had the cluster worked on about 6 weeks ago because despite a new gear the odometer still wasn't working (turned out to be a couple of solder joints). The same weekend I did the blower motor/heater core/thermo trying to limit the amount of time I was without a vehicle. When I put it all back together and put the cluster back in everything seemed great. Then when I finally hopped on the freeway four days later (it's a small town so I don't use I-5 much) I noticed the cruise wasn't working. Thinking that I had just kinked a vacuum hose or simply forgot to put one back on I left it for the following weekend. When I did get around to checking it I went through everything bentley had to offer--fuses, brake lights, adjusting the clutch and brake pedals. No dice. So I then I went about checking all the switches and vacuum pump. No dice. I convinced a shop in Portland to fax me a copy of their cruise control diagnostic checklist and went through that. By removing the cruise control unit and jumping various terminals on the female end of the CCU I ruled out that the vacuum system was good (i had accidentally put "bad" in the original unedited post), as were the switches, stalk switch, etc. According to the checklist I was sent it was down to two things, the CCU, or the Speedo signal that tells the unit that the car is traveling faster than 25mph. Weather was kind enough to send me a working CCU, and that hasn't had any effect. So it would appear that something that was done during that first instrument repair caused the cruise to go out as it worked perfectly before any of the work was done.
Obviously though I'm still open to suggestions. The only other thing that I've tried that may be worth mentioning is that I've removed the carpet again and sanded the grounds at the base of the dash/center console. Any suggestions would help, and I'll be sure to post back when I have the instrument cluster.
|
|
-
|
|
|
I guess you put the yellow wire on cluster connection 203 (what/where ever that is)? I just found that on an abbreviated Mitchell '92 240 diagram but that's all I have.
--
Bruce Young, '93 940-NA (current), 240s (one V8), 140s, 122s, since '63.
|
|
-
|
|
|
There is a double male spade connector on the back of the speedo for speedo output. One of the connectors is used for the cruise control - usually a yellow wire - and the other for the shift indicator on cars equipped with manual trans.
|
|
-
|
|
|
I initially thought about jumping the yellow to the ccu, but I wasn't sure about the best way to do that, and kind of got nervous at the thought of cutting the wire, plugging it into the CCU, etc.
Any suggestions on how you'd do?
|
|
-
|
|
|
I'm not clear on this, but assume you've checked the yellow wire for continuity from end to end. But if you have, I don't see the point in jumpering anything.
And since you're having the cluster worked on, my 2nd assumption is that something tells you the speedo signal is the problem. So again no obvious reason to jumper (bypass?) the yellow wire.
Sorry but I have zero experience with this CC and only limited with the '93 940, which is clearly different (14 pin ccu, OBD "B" output...)
--
Bruce Young, '93 940-NA (current), 240s (one V8), 140s, 122s, since '63.
|
|
-
|
|
|
My Dad checked the continuity for me on the yellow, although it'll be the first thing that I check if the repaired speedo doesn't work. Never hurts to double-check the simpler stuff.
It is my suspicion that it's the signal from the speedo. Now that I've ruled out the vacuum system, it was the only other component of the C.C. system that was worked on/disturbed just prior to it not working. It seems like too big of a coincidence to me that it quit right after working on it. And again, thanks to Weather's replacement CCU, that's really the only piece of the puzzle that hasn't been confirmed working.
Thanks again for all the input on the topic. It's been a big help.
|
|
-
|
|
|
That "exciter" circuit from the panel to the D+ terminal just "kick-starts" the charging. Once the alternator is up and running, that circuit is not active until next time.
Theoretically (I'm not advising this) with the motor running, I believe the B+ terminal (battery +12V) could be momentarily applied to the D+ terminal to "activate" the charging circuit. The alternator would then generate voltage like it always does.
Of course that would still leave you with no instruments or warning lights.
For two 3 hour drives? Not me.
What kind of cluster work is the motivator here?
--
Bruce Young, '93 940-NA (current), 240s (one V8), 140s, 122s, since '63.
|
|
-
-
|
|
Some of these Bosch alternators will "self-excite" above 2000-2500rpm. Our 740's would when the cluster was all screwed up.
I wouldn't drive without the cluster, though.
-Ryan
--
Athens, Ohio
1987 245 DL 324k, Dog-mobile, E-codes
1990 245 DL 137k M47, E-codes, GT Sways/Braces, Dracos, A-cam
1990 744GLE 189K 16-valve project
1991 745 GL 304k, Regina, 23/21mm Turbo Sway Bars
|
|
-
|
|
|
Thanks. I kept insisting that it would, but dear old dad said no way. looks like the student becomes the teacher...
|
|
-
|
|
|
But do you know why?
--
David Hunter
|
|
-
|
|
|
I think it's because the battery charge lamp completes the circuit. From my limited ability to read electrical schematics the power comes in through the fuse box, leaves via fuse 13 (my diagram may not be for my year exactly) and then enters the instrument cluster through the blue-red wire (which lucid pointed out to me is Volvo code for power) on the half-moon connector, then leaves the instrument cluster via the red wire and travels back to the alternator. I think?
|
|
-
|
|
|
the 12v wire to the connector is switched. it should not be hot when your key is out.
|
|
|
|
|
