Water temp gauge not working!!

[tbone714]

So I recently bought a 91 318is, and the temp gauge is not working at all. The two Si battery lights are on, so I know they need to be replaced, but all my othehr gauges work just fine. Is it most likely that the battery is the problem for the temp g not working, or is it a problem somewhere else along the line.

Unknown if this is related, but when I turn my key to the "on" position (not ignition) my auxilary fan comes on at full power. Is this normal for the M42, or is the temp gauge problem causing the aux fan to defect.

Im new to beemers, so laymens terms would be appreciated with your guys' responses, but I am a Certitied mechanic and have been working on subaru's for the last 3 years, so any atempt to help or diagnose will be much appreciated and most likely "understood"

[bmwm42]

Basics: tighten nut behind water temp gauge. Check water temp sensor and wiring.

[N2MYE30]

A good whack on the dash and mine comes alive...not kidding.

[tbone714]

The nut was already tight.

[tbone714]

Which temp sensor are you talking about?

[tbone714]

Still No bueno with this. I guess I'm having two problems now and i'm thinking the second is because of the first..Now I noticed my Aux fan isnt coming on except for when I turn AC on. I've already jumped the high and low speeds, and both work fine (and all fuses and relays are good) but when plugged into the radiator the fan doesn't come on at all. So I'll ask one more time, before I give up and take it to a shop. Is the water temp sensor, the brown sensor nearest the back of the firewall wall, or the blue sensor closer to the front? Anybody's help is much appreciated.


(Is it a possibility the t-stat is bad too?)

[bmwm42]

Brown is sending unit for the dash blue temp sending unit is for the dme

[bmwm42]

You can tell if the tstat is good or bad by doing a couple checks. Do you have heat, does the return hose get hot after a drive or does it stay cool?

[tbone714]

^^^Thanks for the help, I will check to see if it gets hot tonight when I get home.

[Balkanac]

im having a very imilar issue, the aux fan will not go on full speed ever, not even in 40C with the aircon on. i took the plug off the rad and connected the points and it does work at both speeds. I checked all fuses and relays but still nothing. My thermostat is about a year old, and the fan clutch was replaced at the same time. Could this be the switch on the rad?

[tbone714]

Wish I could tell you as i am wondering the same thing

[jlevie]

im having a very imilar issue, the aux fan will not go on full speed ever, not even in 40C with the aircon on. i took the plug off the rad and connected the points and it does work at both speeds. I checked all fuses and relays but still nothing. My thermostat is about a year old, and the fan clutch was replaced at the same time. Could this be the switch on the rad?

If the fan works at both speeds when you jumber the contacts at the temp switch connector, either the radiator never gets hot enough to trip the high limit switch (99C), or the switch is bad.

[bmwm42]

replace that damn switch lol shouldnt be more than 30 bucks for it

[be34st]

A good whack on the dash and mine comes alive...not kidding.

OMG THIS!
+1 this is the same thing I do when mine goes on the fritz.

[Giormelo]

I don't mean to hijack your thread but since you guys are talking about gauges on the cluster, is there any way to test all the gauges and lights on the cluster?

I know and I've done it on my dads x3 that you hold s/r(dont know what its really called) and turn the key to position 1 or 2 etc etc.

Is there anyway to do the same on an e30 cluster?