Idle surging, lights dimming, HVAC and Radio issues - no CEL
10-14-2019, 04:29 PM
#1
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C230 Kompressor Sport
Idle surging, lights dimming, HVAC and Radio issues - no CEL
I've got a 2005 C230K (manual). I have no CEL. Battery tests good. Alternator test good. Voltage looks good (ruling our voltage regulator). Here are my wacky symptoms:
- Idle is sometimes normal but sometimes it surges up just above 1000 RPM, drops to 500 RPM and recovers. This isn't on a regular "pulse", but it does happen every time it's running.
- Lights (dash, dome light, headlight) get brighter then dimmer. Sometimes the HVAC and Radio shut off. I can turn them right back on.
- When warm, sometime when I come to a stop, the idle creeps up to 1200 RPM until I start to drive.
- When very cold or very hot I'll get the red battery/alternator on the digital part of the dash.
- I did have the "light sensor drive to workshop error", which I thought my be the cause, but I changed the rain/light sensor and that error went away.
I'm going to clean the throttle body and spray around for any vacuum leaks. Other than that, has anyone else experienced this or have any suggestions on what next?
- Idle is sometimes normal but sometimes it surges up just above 1000 RPM, drops to 500 RPM and recovers. This isn't on a regular "pulse", but it does happen every time it's running.
- Lights (dash, dome light, headlight) get brighter then dimmer. Sometimes the HVAC and Radio shut off. I can turn them right back on.
- When warm, sometime when I come to a stop, the idle creeps up to 1200 RPM until I start to drive.
- When very cold or very hot I'll get the red battery/alternator on the digital part of the dash.
- I did have the "light sensor drive to workshop error", which I thought my be the cause, but I changed the rain/light sensor and that error went away.
I'm going to clean the throttle body and spray around for any vacuum leaks. Other than that, has anyone else experienced this or have any suggestions on what next?
10-17-2019, 07:05 PM
#3
I've got a 2005 C230K (manual). I have no CEL. Battery tests good. Alternator test good. Voltage looks good (ruling our voltage regulator). Here are my wacky symptoms:
- Idle is sometimes normal but sometimes it surges up just above 1000 RPM, drops to 500 RPM and recovers. This isn't on a regular "pulse", but it does happen every time it's running.
- Lights (dash, dome light, headlight) get brighter then dimmer. Sometimes the HVAC and Radio shut off. I can turn them right back on.
- When warm, sometime when I come to a stop, the idle creeps up to 1200 RPM until I start to drive.
- When very cold or very hot I'll get the red battery/alternator on the digital part of the dash.
- I did have the "light sensor drive to workshop error", which I thought my be the cause, but I changed the rain/light sensor and that error went away.
I'm going to clean the throttle body and spray around for any vacuum leaks. Other than that, has anyone else experienced this or have any suggestions on what next?
- Idle is sometimes normal but sometimes it surges up just above 1000 RPM, drops to 500 RPM and recovers. This isn't on a regular "pulse", but it does happen every time it's running.
- Lights (dash, dome light, headlight) get brighter then dimmer. Sometimes the HVAC and Radio shut off. I can turn them right back on.
- When warm, sometime when I come to a stop, the idle creeps up to 1200 RPM until I start to drive.
- When very cold or very hot I'll get the red battery/alternator on the digital part of the dash.
- I did have the "light sensor drive to workshop error", which I thought my be the cause, but I changed the rain/light sensor and that error went away.
I'm going to clean the throttle body and spray around for any vacuum leaks. Other than that, has anyone else experienced this or have any suggestions on what next?
I would recommend checking it next: https://itstillruns.com/symptoms-bad...r-6063073.html
GL!
11-21-2019, 10:19 AM
#4
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Quick update. I'm thinking voltage regulator. I started going into diag mode and turning to the voltage meter. Sure enough, I'll see it dip down to 11.9/12.0 at times coinciding with the idle surge. Looks like I'm replacing the alternator!
12-06-2019, 10:31 AM
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Alternator was replaced. All of the issues are fixed ... however. Right after startup, I get the batt/alt warning. I think the battery _might_ be starting to go as it dips to 11.0 V during cranking.
Otherwise, once running, the voltage is a solid 14.0 - 14.2 V.
Otherwise, once running, the voltage is a solid 14.0 - 14.2 V.
12-06-2019, 10:57 AM
#6
MBWorld Fanatic!
My OEM Battery when at 12.48 did all sorts of crazy things.
Changed it and all good since.
https://mbworld.org/forums/c-class-w...-replaced.html
Changed it and all good since.
https://mbworld.org/forums/c-class-w...-replaced.html
12-07-2019, 05:00 AM
#7
batts behave badly just before they die
A dying battery will maintain a "surface charge" whereby it will deliver the necessary amps to crank the engine for only a very short time, but the static voltage will look okay or only down a little. If a car with a "surface charge only" battery doesn't immediately start, good luck on your second try - it may crank weakly or not at all, or the engine might just catch and run. In this scenario, you'd running on your alternator output and while loads are low, all may be okay for a time.
In your case, if the alternator and/or regulator was misbehaving, expect a battery low on amps. It may show adequate voltage, but for a definitive battery diagnosis you should go somewhere batteries are sold and ask for a (usually free) load test. If I got a bad result from a load test I'd buy another battery, though not necessarily at the place that load tested it.
In your case, if the alternator and/or regulator was misbehaving, expect a battery low on amps. It may show adequate voltage, but for a definitive battery diagnosis you should go somewhere batteries are sold and ask for a (usually free) load test. If I got a bad result from a load test I'd buy another battery, though not necessarily at the place that load tested it.
