Hi all,

I've finally had a chance to get back to my dead car storage (read parent's house) this weekend to work on my 87. I've posted several times about this over the past couple of months. My fuel pumps are working, the fuel relay is good, there's a spark, so today I was checking the AMM. First I tried disconnecting it and then trying to start the motor (I thought that I'd been told to do this) It wouldn't start. So I tried some of the tests listed in the Bentley. The test was of the heated wire... It said to test at ambient temperature, and it was around 30 degrees outside. I ran the test and it was supposed to fall in between 3.5 and 4.5 ohms, it read .5. I also tried running warm air through meter just for kicks, and it was still very low. According to the Bentley should replace the meter now. I'm not keen on this unless I'm sure that it's bad since a new one is pretty expensive. Can anyone give me some advice on this?

Thanks for your help.

Pete

Pete,

AMM for the 85-87 LH Jetronic regularly goes for less than $45 on eBay from several reliable sources. Better to have a known working engine to system check it on.

Hi Pete,

Before condemning your amm, please check your ohmmeter. I say that because I think it unlikely the wire would fail in this mode. I know it is somewhat more likely a meter's shunt resistor gets damaged with accidental power measured in the resistance mode -- then the meter reads real low. Find something else of known resistance in the 2 to 50 ohm range to compare or try another meter. If the sensor wire fails, it opens up. With the amm plug disconnected, a failed burn-off switch should not affect the measurement of the wire.

Hope its not your amm.

My car just recently had a problem with almost identical symptoms (resistance was 3 Ohms, though, instead of your 0.5). In my case it turned out to be a short in the holder for the 25Amp fuse that sits in the engine compartment.

I would recommend going through the Bentley checklist for ECU inputs.

-Lujo

'88 240DL 172k

Princeton, NJ

there should be a radio supression relay on driverside fender tower. this relay also pulses the injectors. if this fails the car wont start. check it out. good luck. also if amm is bad disconnect it and start the car, it should be able to run without the amm. If it starts only with the amm disconnected the you know the amm is bad.